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

[btt]

Todd,

Too bad we are on opposite sides of the US. I know an Electronics Manufacturing Engineer , who would be willing to help you build product until you have sufficient volume for an ECM.

I would love to have someone else do the assembly, but I don't have the income for that. The budget is already very tight! I think I'm getting it figured out so that there won't be so much production down-time between batches.

 

[FP761]

I would love to have someone else do the assembly, but I don't have the income for that. The budget is already very tight! I think I'm getting it figured out so that there won't be so much production down-time between batches.

I had figured you were already on a tight budget, but I wasn’t specifically looking for compensation. Just wanted to offer assistance towards what has been reported to be an excellent product, not currently available on the market. Great to hear you are able to improve your production efficiency.

 

[btt]

Something I was thinking might be interesting to some of you who like technical details. Why is the P25RX good at receiving LSM? One reason is that the P25RX utilizes a Harris-Rice type of symbol sync code. The code is a modified version of the symsync code in the liquid-dsp library. The modifications mostly relate to DSP co-processor, smaller memory footprint, and adjusting the PLL loop filter for optimized LSM performance. Note that all this magic is performed in firmware onboard the P25RX. (not on the PC software). Note that this approach is much more desirable than a simple Costas loop / Gardner algorithm.

liquid-dsp library documentation

Documentation - liquidsdr.org

liquid digital signal processing library for software-defined radios

liquidsdr.org

Here is a paper describing the concept of a multi-rate symbol sync algorithm utilized by the P25RX

https://www.researchgate.net/profile/Fred_Harris2/publication/3234710_Multirate_digital_filters_for_symbol_timing_synchronization_in_software_defined_radios/links/0046352b45a63f2125000000/Multirate-digital-filters-for-symbol-timing-synchronization-in-software-defined-radios.pdf

 

[kinglou0]

@btt Sent you an email but wanted to just post the promised audio in here as well. Little over 2 hours worth.

.wav as asked for.

Fire Audio for 2 Tone.wav

 

[btt]

@kinglou0,
Thank you!

 

[dcr_inc]

Are those tones taken from a P25 system? or analog?

 

[phillydjdan]

That sounds like analog to me...

 

[Scott73]

This is an interesting idea. It's too bad it does not do Phase 2 systems, trunked DMR, trunked NXDN. For $300 I would expect to do more. Since it only does Phase 1 P25 trunking, $300 is way overpriced and a Phase 1 scanner even used would be under $300. Nice idea though!.

 

[cmjonesinc]

It definitely does p25 phase ii. It's also one of the very few things that handles simulcast incredibly well. It's in fact the only thing that I know of that handles simulcast well that is less than $600 on the market. And unlike uniden and whistler it get's regular updates and improvements. I highly recommend buying one if you can manage to catch them in stock. They sell out almost immediately.

 

[Scott73]

Also the follow talk group/bluetooth button hold button looks fragile. It looks like it would not stand up to a moderate amount of button pushes. Maybe there could be an option to use an external one, or install one that is durable.

 

[rdlafore]

It does do P25 Phase II, and as others mentioned, it handles simulcast interference extremely well. I never knew that I was missing so much traffic on my old 996. I have had no issues with the button, and I frequently use it. I can be "heavy handed" when "mashing a button".

 

[wmlovell]

This is an interesting idea. It's too bad it does not do Phase 2 systems, trunked DMR, trunked NXDN. For $300 I would expect to do more. Since it only does Phase 1 P25 trunking, $300 is way overpriced and a Phase 1 scanner even used would be under $300. Nice idea though!.

Also the follow talk group/bluetooth button hold button looks fragile. It looks like it would not stand up to a moderate amount of button pushes. Maybe there could be an option to use an external one, or install one that is durable.

The P25RX has been capable of P25 Phase II for quite some time now. The button for bluetooth is very solid. Not fragile like suggested. Although this thread is rather long, you should read through it as there is a lot that has been improved in a short time.

 

[kinglou0]

Feel free to e-mail any audio samples (wav files) of the tone sequences for analog or Phase I systems.

That sounds like analog to me...

Correct. As requested. Used an Icom R-30 and exported the recordings to Audacity.

I have the ability to record Phase I and Phase II if needed. My local department is on a Phase II system. If btt needs Phase I or Phase II, he can let me know.

 

[kinglou0]

Are those tones taken from a P25 system? or analog?

Analog.

 

[phillydjdan]

Boy, Scott didn't take the time to read the thread, did he? 😂😂😂

 

[Tinkerwave]

Boy, Scott didn't take the time to read the thread, did he? 😂😂😂

Nor did he take the time to find and listen to any Phase II systems, or press the buttons on this unit. Not sure what device he's referring to, but it isn't the P25RX.

 

[phillydjdan]

I mean, that button is essentially the same push button located underneath the fancy plastic buttons on your typical electronic device. Open up a DVD player and you'll see a bunch of those mounted on the PCB

 

[btt]

The button is rated for 100,000 operations.

-edit: Removed the button color comment. Could be taken the wrong way. (I hate politics).

 

[btt]

Another point regarding the button that I forgot to mention in the previous post is that it has a lower profile than the machine screws that secure the front panel to the enclosure. The machine screw heads provide some protection of the button from dropping, etc.

Button manufacturer:
Typical Applications
• Consumer products
• Instrumentation
• Computer products
• Industrial

 

[btt]

Boy, Scott didn't take the time to read the thread, did he? 😂😂😂

In fairness, this is a long thread as has been pointed out several times. It may be time to start a new thread for general discussion? Suggested titles anyone? 'P25RX General Discussion'?