OpenGD77

What kind of range are people seeing with the GD77 in the HOTSPOT MODE? Please include antenna, power level and any interface data that represents data that can be somewhat replicated.

You should get the same sort of range that you'd get on a simplex QSO on the same power level.

I've not done any detailed rain testing, but I recall getting around 5km range on 70cm, not line of sight. However I can't remember how much power I was using at the time, it may have been as much as 5W.

2m should be better but I have bad QRM here on 2m, which kills the range for me.

Range 15 km
Diamond x300 antenna - 12m mast
5W from the radio from the mobile antenna
Works great. (if it did not block in HotSpot mode)
... I think 20 km can be achieved in the open

HI Piotr,
Not sure what you mean by this - if it did not block in HotSpot mode.
What power level were you running with the GD77?
Were you running VHF or UHF?
Thanks Frederick

FREDERICK. As you know, there is a small error in the file if Radio GD-77 is to work in HotSpot mode (Roger is trying to fix this error) that's why I wrote it.
Performance on the antenna X-300 (12m mast) on the other hand car antenna (on the car) + distance in a straight line 15km Radio GD-77 set to Max power.
I use the 2m band

I was a bit disappointed - '500mW' unmeasured to the shack antenna didnt do noticably better then 12mW from a hotspot (point taken about no over running the pa on the handi though) - but it provides great coverage of the house so no complaints.

One (unrelated ) thing - because there is a received signal strength indicator Im more aware of how marginal my home qth is to the dmr repeater! Previously Id assumed it was rock solid but the gd flicks from half scale to less than a quarter scale without me even moving... this gave me a probably false perception that the opengd77 was a bit deafer than the stock one. ignorance is bliss?

Im very impressed with the scan speed by the way.


Carl GW0TQM

The stock firmware signal indication was always poorly calibrated. The difference between one bar and 4 bars was very small, so in practice it either showed full signal or nothing. It didn't really give any useful indication of signal strength.

FYI.

There around 3dB of variability in the RSSI reading. The current RSSI / signal display is not calibrated, and is derived from an average of RSSI range values I averaged from several radios.

In the longer term we can probably use the RSSI end points from the Calibration table, but the values put into the Calibration table at the factory are totally wrong, Hence people would then need to calibrate their own radios in order to get an accurate reading,

Also.
The same applies to the power.

The Calibration values for power output can often be wrong by a factor of 50%, so unless you calibrate the power of the radio you may be getting considerably more or considerably less than 500mW

And..
There are only power calibration data points for 1W and 5W. Power curve between 1W and 5W is reasonably straight line, so those output power values are fairly accurate if you calibrate you 1W and 5W data points.

However below 1W the power curve gets increasingly non linear, and the only way I could get a reasonably accurate power output on those levels, was to use my radio as a reference and subtract a fixed drive value from the 1W drive value to give the required output.


So... as you can see, what appears on the surface to be trivial is in fact quite complex.

as of this date 21 of april. is there a way to get the hotspot back up to 3 watts from 1. i had good results on earlier binaries further distance in my town. VHF still wont work no matter what so I am using UHF which is quite stable both on gd-77 and Baefeng


thanks for all your hard work


Alec
N1AJW

n1ajw wrote: ↑

Wed Apr 22, 2020 12:19 am

as of this date 21 of april. is there a way to get the hotspot back up to 3 watts from 1. i had good results on earlier binaries further distance in my town. VHF still wont work no matter what so I am using UHF which is quite stable both on gd-77 and Baefeng


thanks for all your hard work


Alec
N1AJW

https://github.com/rogerclarkmelbourne/ ... tspot-mode