New GD77 Beta, and MD9600 Alpha - May 3rd 2022

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oe7abh
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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by oe7abh » Fri Jun 24, 2022 6:13 pm

Hello Roger,

I loaded the firmware 06/22/2022 V5 on my MD9600.
Maximum field strength at 2m (RSSI) - see picture!
Image
70cm is ok - full line !

73 Alfred

VK3KYY
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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by VK3KYY » Sat Jun 25, 2022 1:44 am

oe7abh wrote:
Fri Jun 24, 2022 6:13 pm
Hello Roger,

I loaded the firmware 06/22/2022 V5 on my MD9600.
Maximum field strength at 2m (RSSI) - see picture!
Image
70cm is ok - full line !

73 Alfred
Can you compare the RSSI on VHF with another radio.

I checked my radio and a S9 signal (-93dBm) received on my GD77, also displayed as S9 (-93dBm) on my MD9600.
However, the front end / RSSI voltage from IF seems to saturate at about -78dBm.

I've also noticed another problem, becuase if the radio is in DMR mode, the signal bar goes to 100% but it only goes to 90% if the radio is in FM.
If the radio is in DMR simple mode, it only samples when the DMR signal is present, i.e in the middle of the 30mS signal burst.

I've not noticed this problem on the GD77 but that radio uses a single chip transceiver, whereas the MD9600 has descrete IF's and detector/demodulator chips.

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oe7abh
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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by oe7abh » Sat Jun 25, 2022 7:40 am

Here again the comparison FM and DMR, hardware MD9600-UV-V4A-201111:

2m FM:
Image

70cm FM:
Image

2m DMR:
Image

70cm DMR:
Image

RX: MD9600 without antenna !
Transmitter: Radioddity GD77 50mW, 1m distance
Another device (Yaesu) shows analog on 2m and 70cm -> FULL !

G4EML
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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by G4EML » Sat Jun 25, 2022 9:56 am

It looks like the RSSI measurement range of the IF chips in the V5 is less than the previous chips. It is probably hitting its upper limit before the bar graph reaches the right hand side.
There is probably nothing that can be done about that. To make the bar graph look correct it might need a hack to change the scaling for large signals.

Colin.

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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by VK3KYY » Sat Jun 25, 2022 10:07 am

G4EML wrote:
Sat Jun 25, 2022 9:56 am
It looks like the RSSI measurement range of the IF chips in the V5 is less than the previous chips. It is probably hitting its upper limit before the bar graph reaches the right hand side.
There is probably nothing that can be done about that. To make the bar graph look correct it might need a hack to change the scaling for large signals.

Colin.
The scale above S9 is compressed to 20% (1/5) of the rest of the scale.

Code: Select all

	if ((rssi > SMETER_S9) && (trxGetMode() == RADIO_MODE_ANALOG))
	{
		// In Analog mode, the max RSSI value from the hardware is over S9+60.
		// So scale this to fit in the last 30% of the display
		rssi = ((rssi - SMETER_S9) / 5) + SMETER_S9;

		// in Digital mode. The maximum signal is around S9+10 dB.
		// So no scaling is required, as the full scale value is approximately S9+10dB
	}
For the V5 hardware

It looks like on DMR we already don't get above S9 + 10db, and the code is common between the GD77 and MD9600

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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by G4EML » Sat Jun 25, 2022 11:48 am

It sounds like the V5 hardware has a limited range on FM as well as on DMR so it probably doesn't need the extra scaling applied above S9.

Colin.

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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by VK3KYY » Sat Jun 25, 2022 12:04 pm

G4EML wrote:
Sat Jun 25, 2022 11:48 am
It sounds like the V5 hardware has a limited range on FM as well as on DMR so it probably doesn't need the extra scaling applied above S9.

Colin.
I will give that a try

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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by oe7abh » Sat Jun 25, 2022 3:44 pm

I think,

- no RX-signal (no s-meter line or minimal)
- max. RX-level (full s-meter line)
- in between, deviations can be tolerated !

thank you!
http://tyrofly.at/funk.htm#MD9600_RT90

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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by VK3KYY » Sun Jun 26, 2022 1:19 am

I've now down a fix for this

see downloads/MD9600/Firmware/ef17c1056670a ... 5c1a0cf91e

Maximum signal level on the V5 (aka V4A) hardware is S9 + 15dB instead of S9 + 60dB on the other hardware versions

Signal bar will now show 100% at S9 +15dB, with the scale above S9 being adjusted to accumplish this change.

The RSSI screen has also been changed to display the same as the signal bar, and the graticule lines above the signal bar on the RSSI screen have been changed so that there is difference in the representation of the signal above S9 between the V5 and earlier hardware versions.

I'm not 100% happy with the change to the graticule lines, because there are now only 1 1/2 bars after S9 whereas there were 6 bars after S9 on the other radios, and visually this does not look so good. However it is technically correct.

In case anyone is interested, I found this reference for conversion from dBm to S meter.

https://hamwaves.com/decibel/en/

However we can't completely use it because none of these radios, including the GD77 , ever have a RSSI level below approximately -130dBm, which

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oe7abh
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Re: New GD77 Beta, and MD9600 Alpha - May 3rd 2022

Post by oe7abh » Sun Jun 26, 2022 4:21 pm

VK3KYY wrote:
Sun Jun 26, 2022 1:19 am
I've now down a fix for this

see downloads/MD9600/Firmware/ef17c1056670a ... 5c1a0cf91e

Maximum signal level on the V5 (aka V4A) hardware is S9 + 15dB instead of S9 + 60dB on the other hardware versions

Signal bar will now show 100% at S9 +15dB, with the scale above S9 being adjusted to accumplish this change.

The RSSI screen has also been changed to display the same as the signal bar, and the graticule lines above the signal bar on the RSSI screen have been changed so that there is difference in the representation of the signal above S9 between the V5 and earlier hardware versions.

I'm not 100% happy with the change to the graticule lines, because there are now only 1 1/2 bars after S9 whereas there were 6 bars after S9 on the other radios, and visually this does not look so good. However it is technically correct.

In case anyone is interested, I found this reference for conversion from dBm to S meter.

https://hamwaves.com/decibel/en/

However we can't completely use it because none of these radios, including the GD77 , ever have a RSSI level below approximately -130dBm, which
THANKS Roger for your work, it works on my device!

I've got one more question:
- Is it possible to start the scanner ON THE DEVICE with a long press (arrow down or up)?
I use a stand microphone!

73 Alfred OE7ABH
http://tyrofly.at/funk.htm#MD9600_RT90

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