Addition power settings?
Addition power settings?
I've been sent an update that removes the 750mW power level but adds 50mW as the lowest option instead
I don't know whether the 750mW setting is of any use to people and whether if the 50mW setting is added the 750mW setting should be retained.
the step of 500mW to 750mW is only approximately 1.5dB, so perhaps is not important.
I don't know whether the 750mW setting is of any use to people and whether if the 50mW setting is added the 750mW setting should be retained.
the step of 500mW to 750mW is only approximately 1.5dB, so perhaps is not important.
Re: Addition power settings?
Sounds fine to me. But since there is a large variation in power levels on different GD-77s I would like an option where one can set the output level freely. Somewhat like in the beginning of OpenGD77. Maybe an "Expert Menu (Enter at your own risk)". Just a thought.
73s
Jens
73s
Jens
Re: Addition power settings?
hi, maybe keep the 750 and add a 100 , so 100, 250, 500, 750, 1, 2, 3, 4, 5
just my thoughts
probably not that important.
just my thoughts
probably not that important.
Re: Addition power settings?
DG1YFX wrote: ↑Wed Jan 29, 2020 9:52 pmSounds fine to me. But since there is a large variation in power levels on different GD-77s I would like an option where one can set the output level freely. Somewhat like in the beginning of OpenGD77. Maybe an "Expert Menu (Enter at your own risk)". Just a thought.
73s
Jens
Radioddity (actually TYT who make the radio) don't seem to calibrate the power levels very accurately and put that data into the calibration table.
Originally the firmware allowed people to set the power on a continuously variable scale between 0 and Maximum PA drive.
However most people found this very confusing, because the PA drive level -> power output in Watts, is not linear. Also the power output varies depending on the band (VHF/UHF) and also the frequency in the band.
So every time you change frequency or band you would also need to manually change the power level. Especially as on VHF, its possible to overdrive the PA quite easily, and perhaps do some damage.
With the current system, if people calibrate their radios, the power output will be approximately correctly to around 10%
Re: Addition power settings?
Getting power levels of 1,2,3,4,5 would be very difficult. In fact any power level below 1W is not super accurate
The power curve on the PA highly non-linear between 0W and 1W, and becomes a bit more linear between 1W and 5W.
i.e Below 1W, the mapping between drive level and output is almost exponential.
Between 1W and 5W, the curve goes in the other direction and is much flatter.
My digital power meter seems to stop registering any power below around 50mW, and I think its probably inaccurate below 250mW
Re: Addition power settings?
VK3KYY wrote: ↑Wed Jan 29, 2020 10:17 pm
Getting power levels of 1,2,3,4,5 etc would be very difficult. In fact any power level below 1W is not super accurate
The power curve on the PA highly non-linear between 0W and 1W, and becomes a bit more linear between 1W and 5W.
i.e Below 1W, the mapping between drive level and output is almost exponential.
Between 1W and 5W, the curve goes in the other direction and is much flatter.
My digital power meter seems to stop registering any power below around 50mW, and I think its probably inaccurate below 250mW
Re: Addition power settings?
leave it as it is then
Re: Addition power settings?
These are a couple of power curves for 2 different radios. Both on UHF (437Mhz)
As you can see the drive level number 0 - 4191 (The PA control uses as a 12 bit DAC) needed to produce a specific power, varies a lot between each radio and hence why the calibration contains reference PA drive levels for 1W and 5W for 5Mhz wide chunks of the entire frequency range.
But the calibration only stores the reference value in a single binary byte, which is 8 bits, and is 16 times less resolution than the actual PA control DAC.
If you try to extrapolate the values below 1000mW, you'll see how difficult it is to set an accurate power level with the constraints of a relatively low resolution calibration data, and a highly exponential power curve
Vertical scale is power in mW, horizontal scale is PA drive to the DAC.
As you can see the drive level number 0 - 4191 (The PA control uses as a 12 bit DAC) needed to produce a specific power, varies a lot between each radio and hence why the calibration contains reference PA drive levels for 1W and 5W for 5Mhz wide chunks of the entire frequency range.
But the calibration only stores the reference value in a single binary byte, which is 8 bits, and is 16 times less resolution than the actual PA control DAC.
If you try to extrapolate the values below 1000mW, you'll see how difficult it is to set an accurate power level with the constraints of a relatively low resolution calibration data, and a highly exponential power curve
Vertical scale is power in mW, horizontal scale is PA drive to the DAC.
Re: Addition power settings?
Have you ever done any power usage measurements at the various power levels? I know I've seen some other radios that lowering the power into the finals below factory settings did not actually use any less power. But I'm all for 50mW low, I can touch my hotspot from my chair.
Re: Addition power settings?
I've not actually looked at the current taken at the various power levels.kt4lh wrote: ↑Wed Jan 29, 2020 10:49 pmHave you ever done any power usage measurements at the various power levels? I know I've seen some other radios that lowering the power into the finals below factory settings did not actually use any less power. But I'm all for 50mW low, I can touch my hotspot from my chair.
I agree the 50mW level is a nice thing to add, and perhaps we should retain the 750mW setting.
We could also have a setting where the PA was completely off, but the RF chip will radiate some power even if the PA is off, especially as the case of the radio is not shielded.