P25RX P25 Phase 1/2/DMR Receiver With Bluetooth Audio Support

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kruser

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They do have 700 licenses that do show up. Interesting. That causes me problems professionally because I install public safety BDA/ERRCS systems and have to show the licenses I'm repeating on my site registration. Oh I see it now. They have a whole range licensed.
It's been a long time but I think you can find the actual 700 MHz frequencies in use at a site using a CAPRAD search. I'm pretty sure CAPRAD can be used by all still without registering but that could have changed. CAPRAD was never as user friendly as an FCC ULS search but it was at least a way to find some of the info.
Your link for Ohio is how the Missouri 700 state licenses show up as well, just a range.
 

KC1UA

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Getting a little quiet in here....

I've brought my P25RX to work with me the last few days. I have the fortune of having a spare VHF-HI antenna side mounted near the top of our radio tower that I can use for radio reception. I run it through a 4 port Electroline 2802 multicoupler, the one that compensates for the loss of splitting a signal 4 ways. I have an Airspy Mini that I use there as well, and I've been comparing reception of the two. Our fire department has an antenna on our tower that is also side mounted on the other side of the tower. It is a low band simulcast and when it transmits my Airspy has a fit. (As an aside I know of the potential for a nearby signal and damage to the Airspy; it hasn't happened in over a year so I'm assuming I'm in the clear at this point). I love all of my Airspy devices; they are fabulous, but while it is having a meltdown the P25RX does not seem to flinch. There's no change in the received signal strength and any decoded audio continues along without a problem. Apples and oranges perhaps but just a non-technical observation.

Also the P25RX does very well with adjacent channel reception. Signals of equal strength 12.5 KHz away do not cause any problems with signal attenuation or degradation whatsoever, in my case anyway.

At work, even with the non-resonant antenna, I am able to monitor the one 800 MHz P25 TRS within range and does a dandy job of it. I still haven't taken it mobile or attempted any bluetooth setup with speakers or my vehicle, but all in good time. Some upcoming road trips to do some testing are in order, to be certain.

Pretty pleased so far!
 

amcferrin90

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@btt I finally got to recording a video of what I'm experiencing. I can give you more info regarding locations if it will help. You have my gmail address if you want to do some extensive communications. I won't be driving that route until Monday but I can recreate this sitting still near the house LOS to another multi-carrier tower. Here a link to a video I recorded: VID_20200814_163306.mp4
 
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amcferrin90

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btt

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@btt I finally got to recording a video of what I'm experiencing.
amcferrin90, thank you for the video. It does look like the mega tower is definitely causing some issues. I didn't see the agc respond much to it, so the interference isn't large in-band. The AGC is completely based on what is being sampled by the ADCs and the current front-end-gain-control. As I mentioned before, there are several gain steps for the front end including attenuation, but they are post-LNA. The LNA has a very high OIP3 and the receiver has good blocking, so that must be quite an intense signal and close in frequency. If you can, please try an external attenuator and let me know if that make a difference. Try 10 and/or 20 dB.
 

btt

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Been running mine for a week or so now. Does exactly what it's meant to do. Wish I had bought 2.
There is still more in stock! More than half of the 2nd production run is still available. I just wanted to make sure everyone is aware of that.
 
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station09

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The current pricing is $292. It is true that it currently supports P25 Phase 1 only. DMR and Phase 2 are possibilities for the future firmware developments. Currently, Phase 2 is not operating in my receiving area. If someone can provide some good samples, I could start working on that if there is enough interest in this product.

I have had some success with DMR / Conn+. Still some minor issue with getting the wrong go-to-channel sometimes and some issues with determining correct slot to decode (get voice from both slots sometimes). I haven't touched DMR for some months. Been too busy polishing the configuration software / writing user manual / getting ready for release of the P25RX.

@buddrousa, to answer your question, Here are some features that might be appealing to some:

-Excellent performance with Simulcast system.

-Bluetooth audio streaming. Very nice for mobile operation. Plug it in, pair it with your bluetooth stereo / speaker system the first time, and go. The Bluetooth feature is also handy for a fixed location situation where you want to get the receiver / antenna up higher (on a bookshelf for example) and be able to just turn on a Bluetooth speaker when you want to listen. This is nice for people who just want to listen, but can't get around too good.

-Open-source configuration software with integrated frequency database / test functions that will run on Windows 7, 10, Linux, (possibly Mac)
-Small, rugged, portable, stand-alone aluminum enclosure with USB-C power connector.
-You would be supporting a developer from the USA who needs to start making an income again in order to pay the bills.

As I said before, I could probably lower the price a bit if there is enough interest (volume pricing).
So
 

station09

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So as of now it does not work on P25 simulcast Phase 2 systems> In my area they use a 700mhz P25 simulcast phase 2 system. Be nice to see a unit for that. Thank you
 

btt

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Would love to buy one. But need Phase 2
As mentioned before in this thread, the intention is to get P2 TDMA support added. The control channel code is ready for it and has been validated. Hopefully, it won't be too much longer. Got sidetracked on adding DMR/TDMA support. The DMR support will be released very soon (within the next few days) and then the P2 TDMA support effort will continue. Keep following this thread.

[edit]
Since you quoted a post that is months old, I should probably also point out that the current pricing is $249 and DMR support will have all the issues mentioned in that old post fixed in the upcoming release.
 
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kinglou0

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As mentioned before in this thread, the intention is to get P2 TDMA support added. The control channel code is ready for it and has been validated. Hopefully, it won't be too much longer.
Take your time.

You’re batting a 1000% so far. One man can only do so much and in my opinion, you’ve produced a product that blows away any RTL SDR, Airspy, or SDRPlay and is a lot cheaper than my Unication G5.

I almost exclusively monitor public safety TRS and Uniden or Whistler do not make a product that are worth my time regardless of what many here will say. I don’t need a wide coverage scanner where I have to make compromises.

The P25RX has done an admirable job monitoring the few systems in my area that it’ll work with. I see at least 1 or 2 more coming my way in the near future.
 

btt

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You’re batting a 1000% so far. One man can only do so much and in my opinion, you’ve produced a product that blows away any RTL SDR, Airspy, or SDRPlay and is a lot cheaper than my Unication G5.
kinglou0, thank you for the positive feedback. I really appreciate it.
 

station09

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As mentioned before in this thread, the intention is to get P2 TDMA support added. The control channel code is ready for it and has been validated. Hopefully, it won't be too much longer. Got sidetracked on adding DMR/TDMA support. The DMR support will be released very soon (within the next few days) and then the P2 TDMA support effort will continue. Keep following this thread.

[edit]
Since you quoted a post that is months old, I should probably also point out that the current pricing is $249 and DMR support will have all the issues mentioned in that old post fixed in the upcoming release.
Thank You
 

amcferrin90

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amcferrin90, thank you for the video. It does look like the mega tower is definitely causing some issues. I didn't see the agc respond much to it, so the interference isn't large in-band. The AGC is completely based on what is being sampled by the ADCs and the current front-end-gain-control. As I mentioned before, there are several gain steps for the front end including attenuation, but they are post-LNA. The LNA has a very high OIP3 and the receiver has good blocking, so that must be quite an intense signal and close in frequency. If you can, please try an external attenuator and let me know if that make a difference. Try 10 and/or 20 dB.
I purchased a couple Commscope inline 10 dB pads. I also switched out to a different antenna that we use with cell modems tuned for 700/800, 1800/2100 MHz. I got a lot better results with just one pad inline when in range of multiple towers. Just a reminder this is a 7 site simulcast system and I'm using it while driving. I'm going to try different combinations of antennas and pads to see what works best. The two antennas I'm using that didn't come in the kit are both 1 dBi gain in the 700/800 band.

I noticed in this setup yesterday (without a laptop) that the decoding was better too. I was finding that the decoding even with a green signal indication was ok but audio would still drop out. It doesn't sound like an audio over-driving thing. With the pad and strong signal, the audio was very consistent so I wonder about getting better performance if the AGC is working the signal vs having higher signal come into the device? How much AGC is possible on this? I also did get near one cell tower that killed the signal so I started thinking about harmonics. I know the SDRs are different and use ADC circuits fed by the LNA but in my HF monitoring there are signal images. Just know since I'm seeing that cellular bands are overloading the LNA, the cellular bands are 2.5/5/10/20 MHz broadband transceivers depending on the licensing and band. AT&T has 734-746 MHz, 891-894 MHz that may affect this. Verizon has 776-787 MHz, 869-880 MHz. T-Mobile has 734-740 MHz, 617-642 MHz using 5 MHz at 632.5. If any of those could be creating harmonics? I don't know which SDR you used so I can't look up those specs.
 
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btt

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amcferrin90,

Thank you for reporting on your test results with the external attenuation. It sounds like 10dB does the job. From watching your video, I would say the AGC is not the issue. I don't know what frequency you are operating at for the CC, but I assume it is very close in frequency to one of the tower band edges. The external 10db attenuation is a good solution if it works for you. Harmonics are filtered in the front-end. The P25RX is the SDR. Give me some time to do some measurements. I will add more specs to the user manual.
 

btt

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As I mentioned in an earlier post, DMR support has been added. I would like to give a big thank you to KC1UA. He spent an immense amount of time and effort providing valuable input/design and testing in order to make sure that the initial release of DMR is quite functional. I hope some of you have a chance to give it a try and report on how it works for you. It is available in the "experimental release" on the web site.

Some known things that are missing and will be addressed in future efforts:

Need to implement backup/restore for DMR Config tab.
Need to decode ShortLC frames to obtain the SystemID information. (is always 1 in the current release)
Need to add talk group support in conventional mode.
Need to mute encrypted communications audio (you can disable enc tg)

While I am thanking people for all the input and help with testing, I also need to give a big thank you to relicwr. He has also spent an enormous amount of time with testing various aspects of software/firmware/hardware. There are others who have helped with getting simulcast right that I do not know their user-id here on the forum. Thank you as well!
 

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btt

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There are a few distinct features I forgot to mention about DMR support:

If you monitor conventional DMR and slots are divided between different entities, you can disable the slot you don't want to listen to. This is the reason the option for slot1/slot2, enable/disable are implemented.

When in DMR mode, *all* LCNxx with the "control channel checkbox" enabled will be sampled to check for a control channel on that frequency. If no control-type messages are received within a predefined period, then the next (checkbox-enabled) LCN will be sampled.

If you want to monitor a single frequency in "conventional mode", then enter that frequency in the LCN1 frequency box, and select "conventional".

Please share your experiences with DMR here. The success of this project depends on it.

I was hoping that DMR support would inspire an increase in sales, but so far it has not. (1 sale in 3 weeks).

I'm hoping the reason that people are "holding back" on supporting the P25RX is because of the lack of P2-TDMA support. I will be working every hour I can to get P2 TDMA support added in the next 2-3 weeks. (after that, I will be seeking employment for the next RF job).

Good News:
Some output from some testing today:

$TDMA VOICE GRANT_00, freq xxx.887500, tgroup: 1001
==============================================================================================
grant (0x00) packet_idx 0, tgroup 1001 freq xxx.8875
desc: XXXXX location:
control is switching to monitor grant for talkgroup on freq XXX.887500
==============================================================================================,vqg, $
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
$TDMA found 40-bit P25 Phase II sync @ 6000 sps!
>== Conversation timed-out. Return To Control Channel Frequency

This indicates that the control channel and the P2-TDMA bit-stream @ 6000 sps is working and that P2 support is now on the path to success for the P25RX receiver.
 

boy7777777777

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I am very happy with my p25rx. It is well worth the money spent. Phase2 support should help your sales quite a bit. I am very happy with all the time and effort being put into developing and replying to messages. I don’t know why more people aren’t buying this instead of a uniden or unication. It’s a pretty simple product that works well. Especially for the price. I didn’t want to spend $700 for a scanner that would do simulcast. This is exactly what I’ve been waiting for. It seems to be decoding DMR fairly well for me. I haven’t got to test mobile reception of DMR yet.
 
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