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Amateur Radio VHF & UHF Digital Modes

By Rob Robinette K9OJ

I use a Micro-Node.com Nano-Spot and generic Chinese Jumbo Spot RTQ hotspot for all my digital ham radio needs. They can both do Yaesu System Fusion (YSF), YSF-to-DMR, DMR, D-STAR, P25 and NXDN. I'm using the Nano-Spot for YSF and P25, and the Jumbo Spot for D-STAR and DMR. They both use the very easy to use but powerful Pi-Star software for configuration and control. I got the Jumbo Sport RTQ from aliexpress.com for $115 but it took about three weeks for delivery. Although it runs off a Pi Zero W it performs just as well running Pi-Star as the Nano-Spot with its more powerful dual core processor. The Nano-Spot was $269 (now $299) and took about a month for delivery due to high demand. The Nano-Spot comes in a nice case and has an external WiFi antenna but the two hotspots are functionally almost identical. One problem with the Nano-Spot is it uses a pi 3 clone that with a dual Cortex-A7 sun8i cpu and a custom version of the Linux kernel. The MMDVM firmware can be upgraded by editing the /home/pi-star/MMDVM_HS/scripts/install_fw_rpi.sh file and executing it. The Jumbo Spot uses a Pi Zero W with standard Linux and MMDVM for easy upgrades.

I had a heck of a time getting my digital radios to communicate with my hotspots so I created this webpage to hopefully help new hotspot users get up-and-running easier and quicker than I did.

Micro-Node.com's $299 Nano-Spot Hotspot

See my Nano-Spot Pi-Star settings

 

Jumbo Spot RTQ $125 Hotspot

They both have WiFi, 70cm radio and OLED screen built-in and support YSF, D-STAR, DMR, P25, NXDN and YSF-to-DMR,. See my Jumbo Spot Pi-Star settings.

 


Setting Up The Radios

For me setting up the radios to work with a hotspot was much more difficult than setting up the hotspot and Pi-Star software. Here's a rundown on what I had to do to get each radio setup:

For general troubleshooting I recommend you monitor your radio and hotspot transmissions on an SDR or analog radio so you can verify the hotspot is transmitting and your radio is transmitting in digital mode. If you have an SDR with computer output use it to monitor your radio and hotspot to compare their exact frequency. This can help you quickly dial in the correct Pi-Star RX and TX Offset.

The typical "CQ" call for all these digital modes is simply, "K9OJ is listening".

YSF   Yaesu System Fusion FT1DR

D-STAR   Kenwood TH-D74

DMR   Tytera MD-380

P25   Motorola XTS3000 Model II UHF

My Nano-Spot Pi-Star Settings

My Jumbo Spot Pi-Star Settings

Upgrade Nano-Spot MMDVM_HS Firmware

What YSF, D-STAR, DMR and P25 look and sound like on a waterfall display

Motorola XTS3000 Housing Swap

Modifying Motorola CPS Programming Software For Out-of-Band Frequencies

Motorola XTS2500 & XTS5000 Info

 


YSF

Yaesu System Fusion C4FM is super simple. Just program your hotspot frequency as simplex into the "A" VFO and hit the "Dx" button until "DN" (digital narrow) is displayed and you're all set. The downside to this simplicity is you have to change "rooms" (talkgroups) in Pi-Star. You can't do it with the radio like you can with the other digital modes*. Yaesu has hinted that a future firmware update to their YSF radios will add this capability.

*I have recently read that you can tap into Yaesu's WIRES-X using your hotspot and change rooms but it sounds like a pretty complicated procedure.

Yaesu FT1DR Hotspot Programming

The hotspot frequency is in row 1. A simplex frequency is all that's needed.

Troubleshooting YSF

Monitor Pi-Star's dashboard as you transmit and you should see activity in the "Local RF Activity" section. If you don't:

        Use an analog radio to monitor the hotspot and radio's transmissions. YSF has a white noise static sound to it. It does not sound "digital".

        Verify you're using VFO 1.

        Verify the radio transmit mode is showing "DN" (digital narrow) on the display.

        Check the radio and hotspot frequencies are the same.

        Make sure your radio is in simplex mode when using a hotspot. If you put your hotspot frequency in a repeater band your radio may automatically switch into repeater mode and transmit on the wrong frequency.

        Pi-Star's Admin/Live Logs display will give you more detail on what the hotspot is doing.

        Excessive "Loss" (shown on Pi-Star dashboard) means a network connectivity issue. If your radio transmissions to the hotspot show a high loss then the hotspot's connection to the internet has a problem. If only other other callsigns show high loss then they have a connection problem.

RXOffset & TXOffset

        If you have everything else set right and your hotspot still doesn't acknowledge  your transmissions then you may need to adjust the RXOffset & TXOffset in Pi-Star's Configuration/Expert/MMDVMHost page.

        The RXOffset setting can compensate for an out-of-alignment hotspot receiver or an out-of-alignment radio transmitter. RXOffset adjusts the hotspot's receive frequency in Hz. RXOffset affects the BER (reception Bit Error Rate) shown on the Pi-Star dashboard.

        TXOffset can compensate for an out-of-alignment hotspot transmitter or an out-of-alignment radio receiver. TXOffset affects the BER of your radio--not the BER shown on the dashboard.

        Keep in mind RXOffset and TXOffset are applied to all modes so if you run multiple digital modes they will all be affected. You'll have to tune for the best overall signal and BER for all your radios.

        An RXOffset of -150 (150Hz shift down) on my Nano-Spot worked best for my radios but one ham had to use a setting of 1200 to get his MD-380 to decode DMR from his hotspot (most likely his MD-380 receiver is way out of alignment).

        The Jumbo Spot comes with a sticker that shows the TXOffset and RXOffset need to be set at 500 (+500Hz) right off the bat. My Jumbo Spot liked 400 for both RX and TXOffset. My Nano-Spot did not need a TXOffset adjustment. If the TX and RX offset both need to be adjusted the same amount you can just set the frequency in the main configuration page. For example you can set the hotspot frequency to 446.250500 and set your radios to 446.250 to get a +500 TX and RX offset (leave TXOffset and RXOffset set to 0).

        Once you get everything working you can tune your Pi-Star's "Local RF Activity" BER. If the BER is higher than about 1% then adjust RXOffset to reduce it to a minimum but again, keep in mind the RXOffset is applied to all modes so all the radios you use with the hotspot will be affected. You'll have to tune the RXOffset for the best overall BER for all your radios.

YSF Modulation

Notice the broad, thick, solid waterfall signal. YSF uses 12.5kHz of bandwidth like DMR & P25. YSF sounds like normal static.

YSF uses C4FM (Continuous 4-level Frequency Shift Keying & Frequency Modulation) digital modulation like P25 but the two standards are not compatible.

 


D-STAR

Programming my Kenwood TH-D74 for hotspot D-STAR was difficult with lots of little details that if you get wrong will keep you from communicating with the hotspot. You need to start with registering for D-STAR repeater access so you can use net-linked D-STAR repeaters.

You must enter your callsign into the radio's "Menu (Digital)-TX/RX" page. There is no "D-STAR ID" like DMR and P25 use.

D-STAR Callsign

Enter your callsign in the Menu (Digital)-TX/RX page. When using D-STAR my callsign goes out as "K9OJ/ROB" which is a common D-STAR technique.

 

D-STAR Memory Programming

The hotspot channels run from row 50 to 58.

When programming radio memories you must select the "DR" Digital Repeater mode.

You must also select a "Plus Shift" or "Minus Shift" with a 0MHz offset as shown above (I know, it's weird).

Memory 50 above, "Nano-TN" is the Tennessee-wide Reflector 077C. Notice the "URCALL" column "REF077CL" means "Link to Reflector 077 C module". The "C" must be in the 7th character spot and the "L" must be in the 8th spot.

At far right above, "RPT1" and "RPT2" is where we tell the radio about the hotspot. "K9OJ" is the hotspot callsign and should match what you have in Pi-Star under "General Configuration - Node Callsign". The "B" says to communicate with the "B" module and the "G" means connect through the hotspot's Gateway. The B & G must be in the 8th character spot (I have 3 spaces between my callsign and the B & G). If your hotspot uses VHF then you may need to use "C" instead of "B" (B=70cm, C=2m). RPT1 and RPT2 should match what you have in the Pi-Star D-STAR configuration section, "RPT1 Callsign" & "RPT2 Callsign".

To use the hotspot I select memory 50 (Reflector 077 module C) and transmit for a couple of seconds to get linked to the reflector. The radio will say "Linked to xxxxxx". This step isn't necessary if you have Pi-Star configured to connect to a default D-STAR reflector at startup. Then I change the channel to the talkgroup I want to speak with and transmit.

I use channel 51 (Unlink) to disconnect my hotspot from the reflector or talkgroup when I'm done. Channel 52 is the "parrot" or Echo talkgroup for testing the hotspot and radio. Channel 53 (Info) will make the hotspot tell you the link status. In the URCALL field the U, E and I must have 7 spaces in front of it so it is the 8th character.

Channel 54 is Reflector 001C world-wide. Channel 56 is the Morristown, Tennessee D-STAR repeater. Notice how there is a space between the repeater callsign "W4LDG" and the "CL" (Link to the C module) command because the CL must occupy the 7th & 8th character position in the URCALL column. For most repeaters the B module is a 70cm repeater and the C module is a 2 meter repeater.

Troubleshooting D-STAR

Monitor Pi-Star's dashboard when you transmit and you should see activity in the "Local RF Activity" section. If you don't:

        Use an analog radio to monitor the hotspot and radio's transmissions. D-STAR sounds like a typical digital transmission.

        Verify the D-STAR Callsign is set in the radio.

        Check the memory's Shift & Offset are set for 0 offset.

        Verify the memory's URCALL has the "B" or "C" in the 7th character position and the L, U, E or I in the 8th position.

        Check the memory's RPT1 and RPT2 has the "B" and "G" in the 8th character position.

        Verify the radio transmit mode is set to D-STAR.

        Check the radio and hotspot frequencies are the same.

        Make sure your radio is in simplex mode when using a hotspot. If you put your hotspot frequency in a repeater band your radio may automatically switch into repeater mode and transmit on the wrong frequency.

        If you cannot connect to a D-STAR reflector in Pi-Star verify your D-STAR registration is complete. After registering you have to get approved and then log in to complete your registration.

        Pi-Star's "Admin/Live Logs" display will give you more detail on what the hotspot is doing.

        Excessive "Loss" (shown on Pi-Star dashboard) means a network connectivity issue. If your radio transmissions to the hotspot show a high loss then the hotspot's connection to the internet has a problem. If only other other callsigns show high loss then they have a connection problem.

RXOffset & TXOffset

        If you have everything else set right and your hotspot still doesn't acknowledge  your transmissions then you may need to adjust the RXOffset & TXOffset in Pi-Star's Configuration/Expert/MMDVMHost page.

        The RXOffset setting can compensate for an out-of-alignment hotspot receiver or an out-of-alignment radio transmitter. RXOffset adjusts the hotspot's receive frequency in Hz. RXOffset affects the BER (reception Bit Error Rate) shown on the Pi-Star dashboard.

        TXOffset can compensate for an out-of-alignment hotspot transmitter or an out-of-alignment radio receiver. TXOffset affects the BER of your radio--not the BER shown on the dashboard.

        Keep in mind RXOffset and TXOffset are applied to all modes so if you run multiple digital modes they will all be affected. You'll have to tune for the best overall signal and BER for all your radios.

        An RXOffset of -150 (150Hz shift down) on my Nano-Spot worked best for my radios but one ham had to use a setting of 1200 to get his MD-380 to decode DMR from his hotspot (most likely his MD-380 receiver is way out of alignment).

        The Jumbo Spot comes with a sticker that shows the TXOffset and RXOffset need to be set at 500 (+500Hz) right off the bat. My Jumbo Spot liked 400 for both RX and TXOffset. My Nano-Spot did not need a TXOffset adjustment. If the TX and RX offset both need to be adjusted the same amount you can just set the frequency in the main configuration page. For example you can set the hotspot frequency to 446.250500 and set your radios to 446.250 to get a +500 TX and RX offset (leave TXOffset and RXOffset set to 0).

        Once you get everything working you can tune your Pi-Star's "Local RF Activity" BER. If the BER is higher than about 1% then adjust RXOffset to reduce it to a minimum but again, keep in mind the RXOffset is applied to all modes so all the radios you use with the hotspot will be affected. You'll have to tune the RXOffset for the best overall BER for all your radios.

D-STAR Modulation

Notice the "shoulders" and solid waterfall signal. D-STAR is noticeably thinner on the waterfall display due to its 6.25kHz bandwidth. The other digital modes use 12.5kHz of bandwidth. D-STAR sounds like a "typical" digital signal.

D-STAR stands for Digital Smart Technologies for Amateur Radio. It was developed by the Japan Amateur Radio League and uses Gaussian Minimum Shift Keying (GMSK) digital modulation.


DMR

I really like my Tytera MD-380 DMR UHF radio but it wasn't easy getting it to work with the hotspot.

You have to set your DMR ID in the Pi-Star configuration page and in the radio. If you don't have a DMR ID you can register for your DMR ID here.

Programming memories into a DMR radio is a three step process. You first create "Digital Contacts", then put those digital contacts into "Channels", then put the Channels into a Zone. A Zone is just a grouping of channels.

DMR Memory Programming Digital Contacts

After setting your DMR ID in the radio's "General Setting" page, program your talkgroups in the "Digital Contacts" section. The "Call ID" is the talkgroup number.

 

DMR Memory Programming Channel Information

After entering your "Digital Contacts" above you can plug them into the "Contact Name" field of the "Channel Information" page. Note the "Channel Mode:Digital", "Color Code:1", "Repeater Slot (time slot):1" and "Privacy:None" fields.

I created "Nano-Local" talkgroup 9, "Nano-Echo" parrot, "Nano-USA" USA-wide talkgroup, "Nano-Unlink" talkgroup 4000, "Nano-Info" talkgroup 5000, "Nano-SE-REF" Southeast USA Reflector and "Nano-Texas" Texas-wide talkgroup channels.

DMR Memory Programming Zone Information

The last thing to do is to create a "Hotspot" zone and fill it with the channels you created above. A zone is simply a grouping of channels.

 

BrandMeister Controls in Pi-Star

You can change several DMR BrandMeister controls using Pi-Star's "Admin" dashboard.

I recommend you register with BrandMeister and use their reflectors. I set Pi-Star's "DMR Master" to "BM_United_States_3108" (Atlanta).

To use the hotspot press the MD-380's Menu key to select the hotspot zone.

Turn the radio selector knob to select a reflector. I use BM-SE-REF as my default reflector. Then transmit for about two seconds to link to the reflector. The radio will say, "Linked to xxxxx".

Once linked turn the selector knob to select a talk group if you don't want to speak through the reflector.

DMR talkgroup 3147 is Tennessee-wide. 3148 is Texas-wide, 4639 is USA-wide and 91 is World-wide

We typically use Repeater Slot 1 (time slot 1) and Group Call (not Private Call) for most talk groups.

4xxx talk groups are actually reflectors which can be set as the default reflector.

Once you register with BrandMeister you can edit your hotspot's info for others to see.

You can manually select a new talkgroup on-the-fly in the Tytera MD-380 by hitting the radio's Menu key, selecting Contacts, keying in the talkgroup number (numbers only, no "TG"), then pressing the PTT button to connect.

Once linked turn the selector knob to select a talk group if you don't want to speak through the reflector.

DMR talkgroup 3147 is Tennessee-wide. 3148 is Texas-wide, 4639 is USA-wide and 91 is World-wide

We typically use Repeater Slot 1 (time slot 1) and Group Call (not Private Call) for most talk groups.

4xxx talk groups can be set as the default reflector.

Once you register with BrandMeister you can edit your hotspot's info for others to see.

You can manually select a new talkgroup on-the-fly in the Tytera MD-380 by hitting the radio's Menu key, selecting Contacts, keying in the talkgroup number (numbers only, no "TG"), then pressing the PTT button to connect.

Troubleshooting DMR

Monitor Pi-Star's dashboard when you transmit and you should see activity in the "Local RF Activity" section. If you don't:

        Use an analog radio to monitor the hotspot and radio's transmissions. DMR has a choppy "helicopter" sound to it.

        Verify the DMR ID is properly set

        Check the memory's Channel Mode is set to "Digital"

        Verify the memory's Contact Name is correct

        Check the memory's Color Code is set to 1

        Verify the memory's Repeater Slot (time slot) is correct (usually 1)

        Check the memory's Privacy is set to "None"

        Verify the memory and radio frequencies are the same.

        Make sure your radio is in simplex mode when using a hotspot. If you put your hotspot frequency in a repeater band your radio may automatically switch into repeater mode and transmit on the wrong frequency.

        Pi-Star's "Admin/Live Logs" display will give you more detail on what the hotspot is doing.

        Excessive "Loss" (shown on Pi-Star dashboard) means a network connectivity issue. If your radio transmissions to the hotspot show a high loss then the hotspot's connection to the internet has a problem. If only other other callsigns show high loss then they have a connection problem. You may be able to decrease your Loss % in DMR by increasing Pi-Star's Configuration / Expert / MMDVMHost / DMR Network / Jitter from 300 to 700.

RXOffset & TXOffset

        It seems the DMR mode is more sensitive to radio & hotspot frequency alignment. If you have everything else set right and your hotspot still won't acknowledge your transmissions then you may need to adjust the RXOffset & TXOffset in Pi-Star's Configuration/Expert/MMDVMHost page.

        If you have an SDR with computer output use it to monitor your radio and hotspot to compare their exact frequency. This can help you quickly dial in the correct Pi-Star RX and TX Offset.

        The RXOffset setting can compensate for an out-of-alignment hotspot receiver or an out-of-alignment radio transmitter. RXOffset adjusts the hotspot's receive frequency in Hz. RXOffset affects the BER (reception Bit Error Rate) shown on the Pi-Star dashboard.

        TXOffset can compensate for an out-of-alignment hotspot transmitter or an out-of-alignment radio receiver. TXOffset affects the BER of your radio--not the BER shown on the dashboard.

        Keep in mind RXOffset and TXOffset are applied to all modes so if you use multiple radios they will all be affected. You'll have to tune for the best overall signal and BER for all your radios.

        An RXOffset of -150 (150Hz shift down) on my Nano-Spot worked best for my radios but one Nano-Spot user had to use a setting of 1200 to get his MD-380 to decode DMR from his hotspot (most likely his MD-380 receiver is way out of alignment).

        The Jumbo Spot comes with a sticker that shows the TXOffset and RXOffset need to be set at 500 (+500Hz) right off the bat. My Jumbo Spot liked 400 for both RX and TXOffset. My Nano-Spot did not need a TXOffset adjustment. If the TX and RX offset both need to be adjusted the same amount you can just set the frequency in the main configuration page. For example you can set the hotspot frequency to 446.250500 and set your radios to 446.250 to get a +500 TX and RX offset (leave TXOffset and RXOffset set to 0).

        Once you get everything working you can tune your Pi-Star's "Local RF Activity" BER. If the BER is higher than about 1% then adjust RXOffset to reduce it to a minimum but again, keep in mind the RXOffset will affect all your radios. You'll have to tune the RXOffset for the best overall BER for all your radios.

DMR Modulation

Notice the bands in the waterfall signal. DMR uses12.5kHz of bandwidth and has a choppy, helicopter type sound to it.

DMR stands for Digital Mobile Radio and uses Four-state Frequency Shift Keying (4FSK) digital modulation with Time Division Multiple Access (TDMA) to create two time slots.

 


P25

Commercial P25 radios are very cool and I love the Motorola XTS3000 P25 radio I purchased on eBay. It's a heavy but rock-solid radio that thousands of police and firemen have relied upon for rugged reliable service. There are brand-new housings available for many Motorola P25 radios so you can completely refurbish their look. There are also brand-new batteries and accessories available. The XTS3000 Model I comes with no display or front panel buttons. The Model II has a display and six buttons and the Model III has a display and full keypad. I purchased a used Model II for $169. The XTS3000 comes in VHF, 700/800MHz and two UHF models. The UHF models put out around 4 watts on high and 1 watt on the low setting.

Motorola XTS3000 P25 UHF Radio

The first thing I did wrong was to purchase an XTS3000 UHF Range II with a frequency band of 450 to 520MHz. I didn't realize there were two UHF versions of the XTS3000. Luckily the radio will function just fine on 449.990MHz so that's where I set my hotspot frequency. If you go too far out of the radio's band the CPS programming software won't write the code plug to the radio so I can't use this radio for P25 repeaters. Fun fact: The XTS3000 uses the same antennas, microphones, batteries and charger as the newer XTS5000 but the programming cables and software are different.

The correct UHF radio version for hams would be "UHF Range 1" which covers 403 to 470MHz. Range 1 radios are also referred to as "R Split" radios. Range II radios cover 450- 520MHz and are called "S Split".  I was later able to extend my Range II radio's band down to 440MHz for use with ham repeaters, see Modifying Astro CPS for more info. Later I broke down and purchased a nice Range 1 R Split radio for ham use.

You'll also need a programming cable for the radio. The XTS3000 uses a "Ribless" cable. RIB stands for "radio interface box" and "RIBless" means you don't need a RIB. Ebay sells the cables for around $25 but make sure the seller mentions XTS3000 in the add because the XTS5000 RIBless cable will not work with the XTS3000. The cable clips to the left side of the radio and has either a serial or USB connector to connect to your computer. Mine has a 9-pin serial COM port connector and I use a USB-to-serial adapter with it. I had to set the USB-to-serial adapter for XON-XOFF flow control inside Windows's Device Manager to make it recognize the radio.

The next thing I did wrong was purchase an incorrect version of the Motorola CPS (Customer Programming Software). I ordered the current version which doesn't cover older radios like my XTS3000. After doing some research I found what I was looking for. You can download the Astro Saber and XTS3000 CPS programming software here. The software is no longer available from Motorola.

There is also an Astro 25 CPS version for the XTS2500 and XTS5000. There are also other versions of CPS for newer radios available on eBay so do some research before you buy programming software.

Astro Saber & XTS3000 CPS software only runs on 32 bit Windows 7 or XP. I used Windows 7 and used Window's Device Manager/Ports to see what COM port the USB-to-serial adapter was using and set the USB-to-serial adapter for XON-XOFF flow control. You have to set this COM port number in CPS to establish contact between the computer and radio.

Once I got the correct version of CPS and had the USB-to-serial adapter working it was time to program the radio. P25 radio memory is laid out very much like DMR with talkgroups, channels and zones.

The first thing you should do once you are hooked up is to read the radio data into CPS. Save the code plug if you want to be able to go back to the original programming. Once that is done you can edit and save the data and you'll be able to write it back to the radio.

Programming the XTS3000

One of the most common gotcha's of P25 radio programming is forgetting to set your DMR ID in the radio's ID field. Yes, use your DMR ID for P25. For my XTS3000 the ID went into the "Astro System 1/Genera/Individual ID" field. If you don't have a DMR ID you can register for your DMR ID here.

DMR ID In CPS

In CPS software click on "Expand All" at the bottom of the page, then double-click on "Astro System - 1" in the left window and enter your DMR ID.

 

Setup Channels or "Conventional Personalities"

In the CPS software double-click on "Conventional Personality - 1" in the left window. "Conventional Personality" means "non-trunking channel". Set the transmit and receive frequencies.

 

Set "RX Voice/Signal Type" to "ASTRO" for digital.

 

I set the Transmit Power Level to Low for hotspot use and High for repeaters.

 

Select "293" for the "Network ID" and "C4FM" for "Digital Modulator Type".

 

"Strapped" means the talkgroup can't be changed by using the radio buttons.

 

You have to do the above steps for each talkgroup channel.

Setup Your Talkgroups

I programmed the following talkgroups: TG10100 world-wide, TG10200 USA, TG9999 is Unlink, TG00010 is Parrot.

 

Setup Your Hotspot Zone

I named my zone "HOT" for hotspot.

 

I added the talkgroups to the hotspot zone. A zone is simply a grouping of channels.

Other popular talkgroups include North America TAC1 10201, Canada 302 and Europe 10300.

When you get everything set be sure and save the radio file then "write" the file to the radio. Just connect the radio and turn it on, then click the "Write to Device" button in CPS. The XTS3000 shows "1 CPQ" during data transfer. The radio will reset when finished.

On the radio select the zone, then channel and you're ready to transmit to your hotspot. For my radio Zone 1, Channel 3 is the parrot or echo radio test talkgroup. Anything you transmit to this talkgroup will be sent back to you so you can verify everything works and hear the quality of your audio. Use this to determine how close to hold the radio or mic for best audio.

I like to use the three-position "A B C" switch to select the zone. You do this in the CPS "Controls/Switches" page. You have to put "Zone Select" in both the Conventional and Trunked selections for it to work properly.

Troubleshooting P25

Monitor Pi-Star's dashboard when you transmit and you should see activity in the "Local RF Activity" section. If you don't:

        Use an analog radio to monitor the hotspot and radio's transmissions. P25 has a soft white noise static sound to it. It does not sound "digital".

        Verify the P25 (DMR) ID is set in the radio.

        Check the channel's TX Voice/Signal Type is set to Astro.

        Make sure the channel's Digital Modulator Type is set to C4FM.

        Verify the channel's Network ID is set to 293 for both transmit and receive.

        Check the hotspot and radio frequencies are the same.

        Make sure your radio is in simplex mode when using a hotspot. If you put your hotspot frequency in a repeater band your radio may automatically switch into repeater mode and transmit on the wrong frequency.

        Pi-Star's "Admin/Live Logs" display will give you more detail on what the hotspot is doing.

        Excessive "Loss" (shown on Pi-Star dashboard) means a network connectivity issue. If your radio transmissions to the hotspot show a high loss then the hotspot's connection to the internet has a problem. If only other other callsigns show high loss then they have a connection problem.

RXOffset & TXOffset

        If you have everything else set right and your hotspot still doesn't acknowledge  your transmissions then you may need to adjust the RXOffset & TXOffset in Pi-Star's Configuration/Expert/MMDVMHost page.

        The RXOffset setting can compensate for an out-of-alignment hotspot receiver or an out-of-alignment radio transmitter. RXOffset adjusts the hotspot's receive frequency in Hz. RXOffset affects the BER (reception Bit Error Rate) shown on the Pi-Star dashboard.

        TXOffset can compensate for an out-of-alignment hotspot transmitter or an out-of-alignment radio receiver. TXOffset affects the BER of your radio--not the BER shown on the dashboard.

        Keep in mind RXOffset and TXOffset are applied to all modes so if you run multiple digital modes they will all be affected. You'll have to tune for the best overall signal and BER for all your radios.

        An RXOffset of -150 (150Hz shift down) on my Nano-Spot worked best for my radios but one ham had to use a setting of 1200 to get his MD-380 to decode DMR from his hotspot (most likely his MD-380 receiver is way out of alignment).

        The Jumbo Spot comes with a sticker that shows the TXOffset and RXOffset need to be set at 500 (+500Hz) right off the bat. My Jumbo Spot liked 400 for both RX and TXOffset. My Nano-Spot did not need a TXOffset adjustment. If the TX and RX offset both need to be adjusted the same amount you can just set the frequency in the main configuration page. For example you can set the hotspot frequency to 446.250500 and set your radios to 446.250 to get a +500 TX and RX offset (leave TXOffset and RXOffset set to 0).

        Once you get everything working you can tune your Pi-Star's "Local RF Activity" BER. If the BER is higher than about 1% then adjust RXOffset to reduce it to a minimum but again, keep in mind the RXOffset is applied to all modes so all the radios you use with the hotspot will be affected. You'll have to tune the RXOffset for the best overall BER for all your radios.

P25 Modulation

Looks and sounds very similar to YSF because they both use C4FM modulation. P25 uses 12.5kHz of bandwidth like YSF and sounds like soft static.

P25 (sometimes called APCO 25 or Pop 25) is short for "Project 25" and uses C4FM (Continuous 4-level Frequency Shift Keying & Frequency Modulation) digital modulation like YSM but the two standards are not compatible.

 


My Nano-Spot's Pi-Star Settings For YSF, D-STAR, DMR and P25

See Toshen Golias' excellent webpage for more info on configuring Pi-Star.

 


My Jumbo Spot's Settings for D-STAR and DMR

My Jumbo Spot liked a TX & RX offset of +400.

I'm very impressed with my $115 (now $130) Jumbo Spot RTQ from aliexpress.com. I have ordered many things from aliexpress and haven't had any problems. "RTQ" stand for "ready to QSO" because it comes with a case, antenna, OLED display and Pi-Star loaded 8GB MicroSD Card. You will have to supply a 2.5ma or higher rated power supply with a standard Android phone style microUSB plug. You can just plug it in and it will come up in "Auto AP" mode. Look for a "Pi-Star" wifi source on your computer and join it, sign in with a user name of "pi-star" and password of "raspberry". You can then use a browser to edit the Pi-Star wifi settings then reboot and the Jumbo Spot should join your wifi net.

The Jumbo Spot does everything Pi-Star can dish out: Yaesu System Fusion, D-STAR, DMR, P25, NXDN and YSF to DMR. It took about three weeks for delivery from China but I had to wait longer than that for my American assembled Nano-Spot. Although The Jumbo Spot's computer is a Pi Zero W it performs really well and uses standard raspberry pi Linux and MMDVM_HS for easy operating system and MMDVM firmware upgrades.

Jumbo Spots typically use a 500Hz TX and RX offset so I simply added 500Hz to my desired hotspot frequency. I played around with it and found 400Hz was best for my Jumbo Spot. I'm currently running YSF and P25 on my Nano-Spot and DMR and D-STAR on the Jumbo Spot.

To open the case you remove the antenna then pry apart the upper cover enough to get the tabs clear and pull it off.

 


Upgrade Nano-Spot MMDVM_HS Firmware

My Nano-Spot was delivered with the old 1.0.0 version of MMDVM firmware. I was able to upgrade it to the current 1.3.3 version using the following procedure:

Use Configuration/Expert/Tools: SSH Access to enter the following commands:

cd /home/pi-star/MMDVM_HS/scripts

rpi-rw

sudo su

nano install_fw_rpi.sh

# Modify the following line in the script to the version you want to install. Here I'm upgrading to version 1.3.3:

FW_VERSION="v1.0.0" to FW_VERSION="v1.3.3"

# Change the last line to this:

eval sudo $STM32FLASH -v -w zumspot_rpi_fw.bin -g 0x0 -R -i 3,-2,2:-3,2 /dev/ttyAMA0

# Save the edits: ctrl-o

# Exit: ctrl-x

# Run the script:

./install_fw_rpi.sh

When the script finishes:

halt

cycle the power and verify the upgrade went through

Note: The Nano-Spot uses an Allwiner H3 (sun8i) dual core (2x Cortex-A7) processor. The board is most likely a Chinese Orange Pi+ which is roughly equivalent to a Pi 3. The Orange Pi+ has good hardware specs but little community support and is probably why the Nano-Spot comes with such an old Linux kernel. This does not bode well for the Nano-Spot's long term future and operating system upgrades.

 


Ham VHF and UHF Digital Modes Modulation Video

How the digital modes look and sound on a waterfall display. YSF & P25 sound like white-noise static. DMR has a choppy helicopter type sound and D-STAR sounds like a "typical digital" signal.

 


Modifying Motorola Astro CPS Software To Allow Out-Of-Band (OOB) Frequencies

As I mentioned above I accidentally purchased a UHF Range II (S Split) Motorola XTS3000 with band coverage of 450 - 520MHz (outside of the 70cm Ham band). The UHF Range 1 (R Split) radios with band coverage of 403 - 470 MHz are preferred for Ham use but the 450 - 520MHz radios can be programmed down to 440MHz using a modified Astro CPS program. Standard Astro CPS will allow a slight out-of-band programming like I did for my hotspot at 449.990MHz. CPS will let you know you're out of band but it will still allow you to upload it to the radio. If you try to program a 444MHz or lower frequency CPS will display an error message and not upload the code plug to your radio.

I followed the guidance at this website to modify the AstroPort.exe (Saber and XTS3000 Astro CPS) file to allow programming of XTS3000 450 - 520MHz radios to accept frequencies from 440 - 520MHz. This will allow you to program 70cm repeaters in the 440 - 450MHz range. I believe this is a valid modification for Amateur Radio use. Output power will probably be reduced and performance isn't guaranteed when transmitting out-of-band but my radio performs really well.

While I was at it I also modified Astro CPS for Range I (403 - 470MHz) UHF radios to allow 403 - 477MHz frequencies.

You can download Saber and XTS3000 CPS with the modified "AstroPort.exe" file here. After installing the Saber and XTS3000 CPS program simply replace the original "AstroPort.exe" file with the modified file. The modified file and instructions are in the zip file in a folder called "Modded_AstroCPS".

Astro 25 CPS software for the XTS2500 and XTS5000 can also be modded to allow out-of-band frequencies following the guidance at this website.

 


XTS3000 Housing Swap

I like the look of the firemen yellow Motorola radios so I bought a new Motorola OEM yellow housing for my XTS3000 on eBay and swapped the chassis, control module and "Motorola" placards (front and rear) into the yellow case. There are many YouTube videos that detail the swap but this one is the best. Referencing this video and the pdf linked to below will get you most of the way through the swap. The chassis swap is easy with the OEM Motorola chassis removal tool (eBay) but getting the control module out can be a pain.

It took me a couple of hours to do the swap because I had trouble getting the knobs and knob inserts off and getting the control module out. I also did a ton of Googling and YouTubing to make sure I was doing it right.

Refer to this excellent pdf for chassis removal and reassembly: Batdude's Guide to the XTS3000 & XTS5000.

You must use the Motorola chassis removal tool to get the chassis out of the old case shell without cracking the case. The tool also aids in reassembly. I got my tool on ebay. Just search for "Motorola XTS3000 chassis tool".

From Old Scratched Up Black Case to New Fireman Yellow

You must release the Flex ribbon connector that connects the control module to the chassis as you remove the chassis from the case.

The trick for removing the knobs is to push up on one side of the knob with your thumbs to start that side of the knob up, then push up on the other side of the knob to get it to start up. When you get both sides up a little the knob will slide off.

Below the channel selector knob lives a little "light tube" used to illuminate the channel markings. This light tube is clear plastic and very easy to lose. Watch for it as you remove the channel selector knob and knob insert.

Both of my knobs came off and left the knob insert on the control shaft. If the knob insert stays on the knob shaft you need to use a small jeweler's screwdriver to gently push outward on two little tabs that latch onto the control shaft. Looking down into the insert you'll see the two latch tabs. Move the two tabs just a little outward with the screwdriver while pulling up on the insert will get it to slide off. If you damage the inserts they won't latch onto the shaft and the knob won't be secure. Replacement inserts are available but both of mine were undamaged and reusable.

The volume knob insert has an o-ring that may stick inside the insert or may be left on the control shaft. Don't lose it. Remove it from the insert.

When you remove the radio chassis the control module remains in the case. The control module includes the antenna connector and both knob controls. To remove the control module start with removing the single screw that holds the speaker in place and removing the spring bar the screw holds down. Gently slide the two "Flex" ribbons up out of their slots on both sides of the radio to free them. Make sure the speaker is loose so it can move out of the way when the control module comes loose. When looking into the radio case you want to release the control module's top left locking tab. Insert a small, thin flat-blade jeweler's screwdriver between the control module tab (white) and the case and gently pry the tab until it unlatches. In the disassembly/assembly YouTube video the guy struggles to release the right module tab. It's much easier to release the left tab. Releasing the left also makes it much easier to get the control module out.

There is a small hole in the case to help you push out the front "Motorola" placard. I used a thin pick to push the placard out enough to get a fingernail under it. Use gentle pressure to peel it off and it won't warp or bend. The small rear placard came off with the use of just a fingernail. Warming the placards before removal with a hair dryer can make it easier to get them off without damage. A little general purpose glue will hold them in place on the new shell.

For reassembly remember to remove the new case's inside viewport protective film and try not to get fingerprints on it or the actual display module. Leave the outside protective film on until the radio is fully reassembled.

Insert the control module and simply push it up and snap it into place. Look at the knob and antenna connectors to make sure the module is fully in place and centered. Inspect both control module locking tabs to make sure they are fully engaged.

Gently slide the two Flex ribbons into their slots on both sides of the case.

Install the speaker holding spring bar into place and screw it down. It goes in "bow side up".

Install the knob inserts and knobs. Put the volume knob o-ring on the control shaft first, then install the insert & knob. The control shafts are keyed to line up with knob insert slots. The knobs have indentions that must line up with the shape of the knob insert.

Place the front panel button panel into the new case.

You must make sure the chassis o-ring stays in its groove as you insert the chassis into the new case.

Don't forget to install the speaker screw, install the button pad or to remove the new case's window inside protective film.

Keep the radio display-up when inserting the chassis to keep the display module from coming out of place.

Attach the Flex ribbon to the chassis and gently slide the chassis up into the case as you close it but don't close it all the way.

Use the Motorola chassis removal tool as shown in Batdude's pdf to help snap the chassis fully into the case without damage to the case or o-ring.

In the end the swap went well with no damage and no lost or extra parts. The biggest bonus is the radio looks brand-spankin' new with a new, scratch free display.

 


Motorola XTS2500 & XTS5000 Info

I purchased a VHF XTS5000 P25 radio (136 - 174MHz $130), Ribless programming cable ($27) and Astro 25 CPS programming software ($25); all from eBay. The XTS5000 is one generation newer than the XTS3000 but it is very similar. The XTS2500 & XTS5000 use the same batteries and speaker mics as the XTS3000 but the programming cable and CPS software are different. Make sure the programming cable you get specifically mentions the model radio you have. The XTS2500 & XTS5000 use "Astro 25 CPS" programming software.

The XTS2500 and XTS5000 come in the same lineup as the XTS3000. There are Model I (no display or front buttons), Model II (display + 6 buttons) and Model III (display + full keypad). All models come in VHF, 700/800MHz and two UHF versions. Like the XTS3000 UHF Range I (R Split) covers 403 - 470MHz and UHF Range II (S Split) covers 450 - 520MHz. Since most P25 repeaters and hotspots use UHF, the UHF Range 1 (R Split) radios are best for ham use but they're kind of rare and much more expensive than the XTS3000, especially the Model III with full keypad.

 


MFJ-1278 to TNC-2 Modification

Have an old MFJ-1278 modem lying around? See this to turn it into a stand-alone TNC-2 modem and APRS digipeater.

 


Mini Cooper Ham Radio and Antenna Install

 


WARNING

Tube receivers, transmitters and amplifiers have large capacitors that store enough electricity to kill even when unplugged. If you go into a tube chassis you MUST verify it is unplugged and no voltage remains in the capacitors before working inside it. See Amplifier Safety for more info.

 

Current QSL Card

 

Old QSL Card

The C-141 had two 400 watt HF transceivers, two auto-tuners and one antenna so we had "dual watch" but could only transmit on one radio at a time. The tuners were in a pressurized 7psi container to prevent arcing at high altitude (very low air pressure). The antenna is the "bullet nose spike" on the T-tail. Here's an  Avaition Radio Fundamentals presentation I used to teach C-141 pilots about their plane's radios. We had pretty good reception at forty thousand feet.

 

MajorValve says watch yourself inside that tube chassis.

 

By BrainlessTales.com

Comments and corrections are always welcome at robinette at comcast dot net.

 


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