- Joined
- Dec 21, 2011
- Messages
- 4,987
Are you one of the weirdos who has a 900 MHz XTS2500 or XTL2500/5000 (franken-converted) or XPR5580/XPR7580 sitting around, not being used? You bought it "just because" and had intended to use it "some day", but found most of the smelly hams in your area are unmotivated or unwilling to be progressive and move forward and reciprocate with you on any projects? OK, it's just me.
NOTE BEFORE READING FURTHER: The XPR5580e and XPR7580e do not permit out-of-band operation. Firmware lockdown. Ths lockdown is limited to the "e" models only.
I have been active on 900 MHz DMR and P25 for the last couple of weeks. I gave my bastard radios some new life, with a $35 duplex MMDVM "hat" board which attaches to a Raspberry Pi. I had my doubts due to the price point, but it works and is stable. Power output is as-advertised (10 mW) on VHF and UHF. I have found 900 MHz to be about 1mW, but that is all you will need. I'm 35ft away and my RX RSSI (on 7580) is around -77 dBm on average.
First, here's where I got it: https://www.aliexpress.com/item/4000615367339.html
I'm using it with a Raspberry Pi 4B 8GB. TOTAL overkill on the Pi, but it's what I had available.
What sets this board apart from other hammy contraptions is the DUPLEX capability. This means you can run it as a repeater (separate RX and TX frequencies and antenna ports). The advantage of this:
- Dual timeslots on DMR
- The ability to control the hotspot (via RF) and send "4000" commands duplex (drops dynamic talkgroups)
To get operational, here's what you'll need to do:
- Order the board (splurge the extra $2 or $3 and get the OLED display version)
- Get a Pi or repurpose an existing one. I recommend CanaKit as a vendor for North American hams.
- Find a generic case with open top, so you don't short out your Pi board + have access to the hat/RF connectors
- Potentially consider some 900 MHz SMA MALE rubber ducks. I'm using some Moto 900 MHz ducks with SMA male/male adapters. Not critical.
- Download Pi-Star (Free)
- If you do not already have a MicroSDHC memory card, I recommend a high-endurance model. 32GB is more than enough space. (Canadians, change the URL to .ca)
It really is that simple. You will have to hack your XPR7580 codeplug or CPS to allow for 902-928 operation. I am willing to assist with XPR5580/XPR7580 codeplug edits. NOTE: Firmware must be at R02.09.00.0001 or lower (CPS 16) or you will have to downgrade the firmware through certain methods.
P25 radios are much easier to modify (CPS) for out-of-band operation on 900. I believe the CPS edits are posted here on the board.
------------
So how stable are things? Very. But there are some technical things to be aware of:
- First, update the firmware on the duplex-MMDVM when you get it. The seller is claiming "latest firmware" installed, but it's from August 2018. Updating the firmware is very simple. 1) Bridge the solder pad labeled "JP 1" on the duplex-MMDVM board (enables writing). 2) Login to Pi-Star shell. Then execute the following commands:
rpi-rw (allows writing to the file system)
sudo pistar-mmdvmhshatflash hs_dual_hat (executes the firmware upgrade. When complete, reboot the unit). You will now be at 1.5.2 (11-2020). Mine shipped with 1.4.7 (08-2018). Changelog is here: https://github.com/juribeparada/MMDVM_HS/releases
For good measure, log back in to Pi-Star shell, and do the following:
rpi-rw
sudo pistar-update
This updates the OS, binaries, kernel and libraries to latest versions. When done, reboot.
-------------------
- The seller included a note that stated the TXOffset and RXOffset can be set to 0. OK. Maybe for a dumb, lazy ham. In the real world, we are aware oscillator drift needs to be compensated for. Especially way up at 900 MHz. Log in to the shell again, and execute pistar-mmdvmcal. This is a utility which has what you need to set the TX side. The RX side requires some trial and error (observe the BER via the dashboard). It takes a while, but it's worth the effort. I can describe in better detail if anyone gets stuck. My TXOffset is set to +319 Hz, and RXOffset is set to +185 Hz. I also tweaked my RXLevel to 14 (from default of 50) and it seems to have brought my BER down to 0.3%.
I can post more/go over calibration in more detail if anyone actually decides to pursue the board/setup. I don't want to waste too much time on this if no one decides to play. I am confirming it works and is 100% stable. I'm connected via Ethernet (using Wi-Fi on these things leads to packet loss, as everything is UDP streamed) and my buddies tell me I have zero packet loss, as received.
If anyone else follows through, I look forward to hearing about it/assisting/potentially chatting.
-------------------
And I'd be a total assclown if I did not mention the P25 MMDVM Encryption-capable fork. You can use the hardware I have described, and install the software/firmware (instead of Pi-Star) to chat secure P25, with a crowd that's likely much less prone to mouth breathng, than the ones you WILL observe on BrandMeister and what is now the "public" P25 crowd on the dvswitch.org reflector. Please see this thread:
NOTE BEFORE READING FURTHER: The XPR5580e and XPR7580e do not permit out-of-band operation. Firmware lockdown. Ths lockdown is limited to the "e" models only.
I have been active on 900 MHz DMR and P25 for the last couple of weeks. I gave my bastard radios some new life, with a $35 duplex MMDVM "hat" board which attaches to a Raspberry Pi. I had my doubts due to the price point, but it works and is stable. Power output is as-advertised (10 mW) on VHF and UHF. I have found 900 MHz to be about 1mW, but that is all you will need. I'm 35ft away and my RX RSSI (on 7580) is around -77 dBm on average.
First, here's where I got it: https://www.aliexpress.com/item/4000615367339.html
I'm using it with a Raspberry Pi 4B 8GB. TOTAL overkill on the Pi, but it's what I had available.
What sets this board apart from other hammy contraptions is the DUPLEX capability. This means you can run it as a repeater (separate RX and TX frequencies and antenna ports). The advantage of this:
- Dual timeslots on DMR
- The ability to control the hotspot (via RF) and send "4000" commands duplex (drops dynamic talkgroups)
To get operational, here's what you'll need to do:
- Order the board (splurge the extra $2 or $3 and get the OLED display version)
- Get a Pi or repurpose an existing one. I recommend CanaKit as a vendor for North American hams.
- Find a generic case with open top, so you don't short out your Pi board + have access to the hat/RF connectors
- Potentially consider some 900 MHz SMA MALE rubber ducks. I'm using some Moto 900 MHz ducks with SMA male/male adapters. Not critical.
- Download Pi-Star (Free)
- If you do not already have a MicroSDHC memory card, I recommend a high-endurance model. 32GB is more than enough space. (Canadians, change the URL to .ca)
It really is that simple. You will have to hack your XPR7580 codeplug or CPS to allow for 902-928 operation. I am willing to assist with XPR5580/XPR7580 codeplug edits. NOTE: Firmware must be at R02.09.00.0001 or lower (CPS 16) or you will have to downgrade the firmware through certain methods.
P25 radios are much easier to modify (CPS) for out-of-band operation on 900. I believe the CPS edits are posted here on the board.
------------
So how stable are things? Very. But there are some technical things to be aware of:
- First, update the firmware on the duplex-MMDVM when you get it. The seller is claiming "latest firmware" installed, but it's from August 2018. Updating the firmware is very simple. 1) Bridge the solder pad labeled "JP 1" on the duplex-MMDVM board (enables writing). 2) Login to Pi-Star shell. Then execute the following commands:
rpi-rw (allows writing to the file system)
sudo pistar-mmdvmhshatflash hs_dual_hat (executes the firmware upgrade. When complete, reboot the unit). You will now be at 1.5.2 (11-2020). Mine shipped with 1.4.7 (08-2018). Changelog is here: https://github.com/juribeparada/MMDVM_HS/releases
For good measure, log back in to Pi-Star shell, and do the following:
rpi-rw
sudo pistar-update
This updates the OS, binaries, kernel and libraries to latest versions. When done, reboot.
-------------------
- The seller included a note that stated the TXOffset and RXOffset can be set to 0. OK. Maybe for a dumb, lazy ham. In the real world, we are aware oscillator drift needs to be compensated for. Especially way up at 900 MHz. Log in to the shell again, and execute pistar-mmdvmcal. This is a utility which has what you need to set the TX side. The RX side requires some trial and error (observe the BER via the dashboard). It takes a while, but it's worth the effort. I can describe in better detail if anyone gets stuck. My TXOffset is set to +319 Hz, and RXOffset is set to +185 Hz. I also tweaked my RXLevel to 14 (from default of 50) and it seems to have brought my BER down to 0.3%.
I can post more/go over calibration in more detail if anyone actually decides to pursue the board/setup. I don't want to waste too much time on this if no one decides to play. I am confirming it works and is 100% stable. I'm connected via Ethernet (using Wi-Fi on these things leads to packet loss, as everything is UDP streamed) and my buddies tell me I have zero packet loss, as received.
If anyone else follows through, I look forward to hearing about it/assisting/potentially chatting.
-------------------
And I'd be a total assclown if I did not mention the P25 MMDVM Encryption-capable fork. You can use the hardware I have described, and install the software/firmware (instead of Pi-Star) to chat secure P25, with a crowd that's likely much less prone to mouth breathng, than the ones you WILL observe on BrandMeister and what is now the "public" P25 crowd on the dvswitch.org reflector. Please see this thread: