Possible problems with RSSI / ACG

VK3KYY
Posts: 7483
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: Possible problems with RSSI / ACG

Post by VK3KYY » Mon Mar 15, 2021 11:26 pm

BTW.

I split the posts about the RSSI / AGC to a new thread.


There may be some undocumented command that needs to be sent to the AT1846S to reset the AGC when changing channel, but at the moment we are not aware of anything like this.

I know the RSSI and Noise / deviation, values get reset when the channel is changed, or when the Rx is turned e.g. after transmission finishes, and also as part of the power saving.

But I don't know about the AGC and there is nothing in the datasheet about needing to reset the AGC when changing channels, and also nothing in the AGC about whether its possible to reset the AGC

Nat
Posts: 21
Joined: Fri Nov 27, 2020 11:09 pm
Location: Italy

Re: Possible problems with RSSI / ACG

Post by Nat » Tue Mar 16, 2021 12:05 am

Ok for the thread.

I understand your hard work. It gets even harder when there are no enough info/data.

For RSSI bar layout, it was just a suggestion. I agree with you.

Go ahead like this.

Ciao.

Nat

User avatar
WY7JT
Posts: 13
Joined: Thu Apr 09, 2020 4:49 pm

Re: Possible problems with RSSI / ACG

Post by WY7JT » Tue Jun 08, 2021 7:07 pm

I noticed a possible RSSI bug today. The S meter was half scale, and with my digital hotspot it's usually full. Normally the RSSI on receive is -81 dBm, -128 dBm with no signal. But when the meter was half scale it was approximately -120 dBm with signal, and -140 dBm with no signal. So I turned the radio off and on and it went back to normal. I think in the last couple days I heard someone on the OpenGD77 talk group mention they were getting some strange RSSI readings. I'm running the latest firmware compiled from source, and hadn't noticed this before. The radio was on Eco 3.

BTW, loving the new firmware and added database space especially if you sacrifice the voice prompts. Side note, since we're using the latest grab of the AMBE codec from the official firmware, is it just me or does the receive audio sound better? Or was something changed in the firmware and I missed the note?

Jason

VK3KYY
Posts: 7483
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: Possible problems with RSSI / ACG

Post by VK3KYY » Tue Jun 08, 2021 10:55 pm

WY7JT wrote:
Tue Jun 08, 2021 7:07 pm
I noticed a possible RSSI bug today. The S meter was half scale, and with my digital hotspot it's usually full. Normally the RSSI on receive is -81 dBm, -128 dBm with no signal. But when the meter was half scale it was approximately -120 dBm with signal, and -140 dBm with no signal. So I turned the radio off and on and it went back to normal. I think in the last couple days I heard someone on the OpenGD77 talk group mention they were getting some strange RSSI readings. I'm running the latest firmware compiled from source, and hadn't noticed this before. The radio was on Eco 3.

BTW, loving the new firmware and added database space especially if you sacrifice the voice prompts. Side note, since we're using the latest grab of the AMBE codec from the official firmware, is it just me or does the receive audio sound better? Or was something changed in the firmware and I missed the note?

Jason
Re: RSSI

Daniel found a bug in the RSSI yesterday, which will be fixed in the next release,but it could be a different bug to the problem you saw.

Re: AMBE codec

Its impossible to know whether they updated the codec in the newer official.

The locations off the AMBE codec functions in the official firmware changed, which required changes to the OpenGD77 firmware, but only in terms of memory block reservations and addresses to access the functions.

It was non-trivial to update to the new official firmware. I had to crack the latest firmware encryption key decrypt the new official firmware and then search for the locations of the ambe functions in the new official firmware.

I use a hacking tool developed by the NSA for this, and requires many hours of work.


That aside.

I have rewritten some other parts of the firmware related to the interface between the firmware and the AMBE codec, and its possible that those parts now run faster.

However whether these changes would make any differnce, its hard to know, and my gut feeling would be that any changes are inside the AMBE codec

Post Reply