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FreqNout

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The size of the device without the battery option would be approximately 2.5 x 0.75 x 0.5 inches.
Super cool news.

Seriously, this design concept could be configired to add RX modules to the base model.

I do not believe there currently is a 2 receiver p25 scanner in marketplace.
If the design allows to add multiple receivers to work as a system that would be a new concept.

Multiple receivers allows for dedicated antennas per rx. Spacial diversity to improve mobile performance in multi path areas could be acheived. As well as other increased performance by having more than one rx tuner.

A 'system' concept of connected receivers goes beyond the current idea of buying multiple scanners.
 

btt

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Maybe that is the direction this should go. A multi-channel system where you can add as many as you need to cover an entire system with highly selective, narrow-band receivers. The main CPU (PC / RPi) could work on using the demodulated/decoded streams efficiently for whatever application instead of 8-cores all running at 100% brute force to decode a wide-band IF of several MHz wide.
 

KevinC

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I think we're off-topic from the thread, but Todd seems fine with it.

A 700 only or 800 only device would be completely useless in my area. Not only do we have both bands, we have sites with both bands in them.
 

btt

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I think we're off-topic from the thread, but Todd seems fine with it.

A 700 only or 800 only device would be completely useless in my area. Not only do we have both bands, we have sites with both bands in them.
In that case, you would need two or more receivers with the system concept that FreqNout is getting at. This would give you several potential advantages in addition to blocking the cell tower downlink frequencies.
 

KevinC

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In that case, you would need two or more receivers with the system concept that FreqNout is getting at. This would give you several potential advantages in addition to blocking the cell tower downlink frequencies.

Got it!
 

FreqNout

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Maybe that is the direction this should go. A multi-channel system where you can add as many as you need to cover an entire system with highly selective, narrow-band receivers. The main CPU (PC / RPi) could work on using the demodulated/decoded streams efficiently for whatever application instead of 8-cores all running at 100% brute force to decode a wide-band IF of several MHz wide
Just brainstorming your small design to allow for multiple rx to work as a system.
It could be open source (to get back on topic)
 

freqseeker

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I like where this is going. I have always said the more you scan the more you miss and that's a fact. For decades I have had multiple scanners running at once. One is primarily for my city and interagency channels. Others I tune where the action is.

I can appreciate the single band subscriber quality receiver. I see the problem is when a system uses two bands (one of my local systems does just that). The ability to link multiple receivers as @FreqNout suggests would be great. There will always be give and take. The only scanner that can compete right now is the Uniden SDS line, they are still nearly $700 and to me the receive and audio performance is not nearly as good as the P25RX line.
This approach will not be for everyone, but you can customize for your location. Don't forget subscriber quality vs a general scanner. I'm all about quality not quantity. Depending on the price point you could have a much better monitoring station vs a Uniden SDS.
You can watch a action movie on your flat screen with its built in speakers or you can spend hundreds to thousands for a surround sound system, it's a matter of what is worth it to you. My P25RX's destroy any scanner I have ever owned.
 

goldmyne99

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I can appreciate the single band subscriber quality receiver. I see the problem is when a system uses two bands (one of my local systems does just that). The ability to link multiple receivers as @FreqNout suggests would be great.
This approach will not be for everyone, but you can customize for your location.
The single band unit without bluetooth that @btt has described would meet my needs. My P25RX sits on one 850 system and uses lineout for audio. That sounds a lot like this new design.

If bluetooth/wifi is needed, there is always the possibility of using the hardware in a Wio Terminal device.

The 'system' concept of linking muliple RX tuners/modules is a big deal. Adding a linked low cost 2nd or 3rd RX allows for system performance features not available by simply buying another scanner.
 

btt

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Good news regarding the new board. P25 simulcast is being demodulated, decoded, and audio synthesized on the new digital board. I'm very confident that this is going to work now. The attached screenshot is using baudline to view the filtered I/Q samples as they are streamed via UDP over the emulated-Ethernet network interface. The console showing text decode is a telnet session over the same interface for debugging. (telnet server running on the device). I will create a new thread after this post for the new development. I need to switch to customer support mode now. This is a great place to stop.
demod_baudline_telnet.png
 

maus92

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Thank you for the feedback. You did read that correctly. The filters allow blocking of cell tower downlinks. The idea is to create an affordable device that monitors a system with subscriber-like RF performance. If enough people see this as a negative, I will change the design. I may offer an option for battery/no battery. Keep an eye on it. You might change your mind after more details emerge.
There are many systems that have both 851-860 and 769-775 channel resources, sometimes on the same site. Just reiterating what others are stating that it would be imperative to have this capability.
 
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btt

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There are many systems that have both 851-860 and 769-775 channel resources, sometimes on the same site. Just reiterating what others are stating that it would be imperative to have this capability.
Yes, a few people have pointed out this unfortunate reality. If it is desired to completely block the cell tower downlinks in a system like that, there are a couple of choices. 1) Add RF switches and 2 paths through 2 bandpass filters, or 2) Use 2 receivers with 2 different bandpass filters. I will consider both of these options in addition to the option of leaving the filters off.
 

rr60

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Some general feedback. For me near perfect subscriber like decode performance interest very high. Cell 5G desense rejection interest also very high. Cell towers when mobile shut down the G5 frequently. There are many of these towers. 767MHZ burning here -100dB. Totally cool with concept of linking two devices to cover 700/800.

Thanks for you hard work and interest. Crowdsourcing? Keep us posted @btt
 

ra7850

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Todd,

The latest update does in fact resolve the missing mode column from the Radio Reference files. I'm still seeing the issue of the one group we discussed not being able to be imported.

Robert
 

btt

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Todd,

The latest update does in fact resolve the missing mode column from the Radio Reference files. I'm still seeing the issue of the one group we discussed not being able to be imported.

Robert
Thanks. I will work on this today. I will email you a little later.
 
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