Hi,
The time constant is automatically & dynamically adjusted as Lars code modified by PA3FYM and me.
DEMA is calculated every time and tc increase and decrease regarding GPSDO performance.
These are first results from John Miles, KE5FX software TimeLab.
EDIT: Images have no valid data.
Hi,
Hardware and software for microcontroller is completed. A voltage value 0-3300 mV is transmitted to USB every 1 sec. BNC connector is giving the voltage to be measured for a scope or a voltmeter.
Link : I will try to feed data to it.
the control loop is much too fast.
Hi,
Can you explain your consept?
I use Lars GPSDO with 100 MHz OCXO instead of 10 MHz.
Hi,
Developing a small frequency difference measuring system for comparing the GPSDO with Cesium 10 MHz frequency standard. Here how a 1 Hz frequency difference seen in a digital scope. Data will be captured and plotted.
Hi,
The results: 3 mW transmitted at 80 cm offset dish with POTY antenna, as received by 90 cm offset dish using a twin Octagon LNB and of course the new low phase noise GPSDO.
Hi,
The low phase noise GPSDO is completed.
Outputs: 2* 1PPS TTL, Locked (open collector), 100,50,25,10,5,1 MHz sine 10-20 dBm and 2*25 MHz 18 dBm for LNB.
Power supply: 4-30V.
Hi,
The height in my case is 20mm.
Before adding yours to the PCB you can create a test one to measure it's performance.
Hi iw5bsf ,
A 28 mm (30 external) pipe cup was used.
My proposal is to use this way to secure the screw.
Hi,
In practice I have a modified Octagon twin LNB. The unmodified ones receive WB beacon when transponder is empty 10.5 MER. With the current GPSDO the simple modified one receive it with 10.1-10.2 MER. About 0.1 to 0.2 better is if I add a inductance in series with meander of LNB. When I try in the past only the 100 MHz OCXO with a 74AC74 divider /2&/2 producing 25 MHz the 10.5 MER could be archived with the simple modify LNB. So I try now to use the new LNB (I use that now...) with 100 MHz OCXO in GPSDO. We will see the results.
Regarding your post I will not try to improve modulators phase noise but LO LNB's phase noise. The result is the same.
We must not forget that LO (9750) is 390 * 25 MHz so phase noise is increased too much.
Hi DC7KG ,
I know and I use these software tools.
Unfortunately to measure phase noise you need a spectrum analyser with better phase noise than the signal to measure. I have make phase noise measurements but this GPSDO, if all works fine, will have a lower phase noise than I can measure. I measure it indirectly by measuring MER of WB beacon feeding the LNB with 25 MHz. I will try to find here in Greece a phase noise instrument. First I will have to put it into a box and finish construction. I will have also to convert 3.3V to TTL level the 1 PPS signal. I will keep informed here for the results.
PA3FYM A GPSDO with low phase noise 100 MHz OCXO is working.
Hi,
Converting a 4€ Amiko L107 LNB to 10-12 GHz down converter, adding also a 12V bias tee.
NEW DATV BEACON SETTINGS
1) DATV Beacon DVB-S2 parameters
- DVB-S2
- QPSK 4/5 FEC
- 1500 kSymbols
- RollOff = 0,25
- Pilots = off
- min. C/N = 4.6dB
- Datarate 2.383 MBit
2) Center Frequency: 10.4915 MHz
Hi,
Is these the latest settings?
Also there is an unanswered question about normal or short FEC frames. From igor/dvds2rx got that is normal. Is that so?
Hi,
How it can be explained, if I got it, that rolloff displayed is 0.2 and setting is 0.25?
Hi,
If is so the TS transmitted rolloff must match the actual rolloff?
Hi George,
from what do you conclude that the rolloff should / could have changed ?
73 de Robert
Hi,
In the screen dump with red circle there is 20 which must be roll-off. Is that so?
Hi,
The rolloff has changed to 0.2 ?
Hi,
Trying to receive WB beacon using igorauad OOT module is in progress...
Hi,
A pair of GNURadio flowchart created permitting remote NB QO100 operation. A bandwidth of about 1 Mbit is used in both directions. A FFT spectrum of all the transponder is visible remotely and a waterfall of 8 KHz used is visible also. The important is that IQ data is transmitted in both directions and any possible NB mode is capable remotely. In other words mode is independent of server side. PTT signal is also available remotely. ZEROMQ is used for passing data and control signals.
NEW DATV BEACON SETTINGS
1) DATV Beacon DVB-S2 parameters
- DVB-S2
- QPSK 4/5 FEC
- 1500 kSymbols
- RollOff = 0,25
- Pilots = off
- min. C/N = 4.6dB
- Datarate 2.383 MBit
2) Center Frequency: 10.4915 MHz
The FEC is normal (64.800) or short (16.200) ?
