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Topics - SP5WWP

Technical / ADF7021 problem
February 01, 2020, 06:58:09 pm
Does anyone have mmdvm board and can help me? I have a problem with writing to ADFs registers. I can provide a hex for STM reflashing.
Technical / M17 - modulation
December 21, 2019, 09:50:22 pm
2FSK or 4FSK?
Technical / TR-9 - RF power amplifier
December 09, 2019, 07:38:37 pm
The RF part of TR-9 uses an Si4463 chip (+20dBm output) along with a power amplifier based on AFT05MS004NT1 MOSFET (about 20dB of gain). When we are going to use the ADF7021 instead, the output level of it (+13dBm) won't be enough to drive the PA. What I suggest is to use a MMIC like this one before the output stage:
Technical / Si4463 RX problem
December 06, 2019, 08:28:55 pm
I've configured one Si4463 to transmit v3 packets and it works well, the first packet is 85ms and all other 80ms long. But when I try to detect them (with another Si4463), it only detects the first one (probably because it contains a preamble). Does anyone have any experience with Si446x chips or can buy like 2 and test them? Modules are like $3.5/each.

PS Yes, I have disabled the preamble detection (I think).
Technical / TR-9 analog mode?
December 05, 2019, 11:32:20 am
I have just came up with an interesting idea. If we can use ADF7021 instead of Si4463, we could possibly implement analog FM too.
Transmitting could be done by modulating the VCO externally (via the "VCO IN" pin) and sending the same symbol constantly (to get the carrier).
Receiving: enable internal AFC (to track the FM carrier) and take voltage input of the VCO (again - the "VCO IN" pin).

What do you think? Si4463 can only allow analog TX, because there's no VCO control voltage anywhere, but you can still modulate the VCTCXO.
General discussion / Requests - forum
December 04, 2019, 10:09:49 am
Do you think we're going to need a latex parser plugin here? OFC we do :-) Use latex bb-tags.

General discussion / M17 logo and a splash screen
December 02, 2019, 02:46:42 pm
As in the title - do we need a simple logo? Second question - i have prepared a splash screen for the TR-9 that is very basic. Link here: The format is RAW, RGBA, 8/8/8/8.
Technical / Error Correction Coding
December 02, 2019, 12:01:34 pm
I'm using a simple Hamming (7,4) now and apply it to every singly nibble. It obviously needs improvements. There is no bit re-ordering applied.
faydrus recommended using libcorrect (Reed-Solomon or convolutional coding). I can't run any of the example tests :(
Technical / TR-9 - case
December 01, 2019, 03:41:02 pm
I think it would be nice to have a case similar to this one:

There should be two versions of this radio. One with a display and one without it. The one without might look just like that BD300 above. Of course, we don't want a 1:1 copy, that's just for reference.
Technical / TODO list
November 29, 2019, 09:42:42 am
M17 standard:

  • a lot of brainstorming to make M17 well-fitted for hams

  • formalize the standard

TR-9 radio:

  • move the schematic and board layout from EAGLE to KiCAD

  • optimize the RF part (trace impedance)

  • check doppler effect influence on reception

  • design a case

  • think about a version without a display (?)

  • merge keyboard and display boards into one

  • bypass R20 and R23 with 33p caps

  • add PWR_ON signal for the GPS module

  • add 4.7k pull-up resistor for the PTT microswitch

  • remove 5V voltage regulator

  • enable hardware AES

  • add a GNSS module

  • add a compass chip

  • replace goldpins for better connectors (keyboard and GNSS module connectors)

  • dynamically change the clock, we don't need to run full 216MHz on idle

  • switch to ADF7021 chip

  • add a MMIC before the output stage

M17 repeater:

  • add power envelope control

  • finish telemetry website

  • add some more info on the front display

General discussion / M17 gallery
November 26, 2019, 06:36:04 pm
Warning! Long post :)

ETSI standards on DMR and TETRA

An early TR-9 prototype

Me holding an incomplete TR-9 radio (a prototype is visible in the background)

Showing Equipment Identity Numbers on the display

AD8318 RF detector and a current probe output - frames are clearly visible

M17_ANL board

M17_ANL output level testing with an AD8318

M17_ANL, programmed and ready to work!

Repeater power amplifier (S-AU82L module)

...its current consumption


SR5MS duplexer
Technical / M17 frame description
November 26, 2019, 10:39:46 am
Still a subject to change!

Framing description and ECC scheme (ODF)

Extract (stream mode):

Frame generator for SDR (eg. HackRF), sends null data (TODO: fill it with Codec2 data):

GNU Radio Companion .grc file for M17 4FSK modulator with RRC filtering:
Technical / M17 hotspot with M17_ANL and Raspberry Pi
November 26, 2019, 10:34:43 am
An M17_ANL can be used with Raspberry Pi to make a hotspot. Why RPi? Because it's widely available, cheap and popular. Also, it has an Ethernet connector and can be programmed using Python, C - virtually anything.
Technical / M17 - SDR & GNU Radio
November 26, 2019, 10:32:33 am
M17 compatible radio built using RTL-SDR/HackRF and GNU Radio.
General discussion / FAQ
November 26, 2019, 10:25:13 am
Technical / TR-9 - schematics and firmware
November 25, 2019, 09:22:26 pm
TR-9 is a handheld radio for the M17 system.

TR-9 schematic in PDF: