MY QO100 SETUP

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.

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,

The results of phase noise improvements in GPSDO.

Receiving is with 90 cm offset dish, modified Octagon twin LNB.

Quote from iw5bsf

I took the copper caps like yours I have to make the center hole, did you measure the loss of 2.3ghz?

Hi Roberto,

It depends from the feeding wires (probe) length.

For more info see the W1GHZ guide : Link

Hi,

After a lot of tests the solution to Winzel low phase noise GPSDO, which have big frequency variations due to thermal stabilization internal circuit, was to run the Lars original software with TC = 16. The Alan deviation was improved, but most important it stopped to unlock as big TC leads to PLL unlock.

Hi,

In order to align my portable system dish (but not only to this), a ICOM Q7 used as a portable 739.5 or 740 MHz FM receiver seems suitable to do the job. A set of a 10 dB and a 20 dB attenuators give proper S meters readings used in any combination. Any similar experience?

Hi,

A out of topics HF spectrum analyzer project.

Hi iw5bsf Roberto,

I am not sure about your setup so I must not give you any information as they can be wrong.

Hi,

A GNURadio generic SNR calculation routine is built as an extended Python block. It takes a IQ data stream (usually a narrow one - a few kHz) and gives SNR as a real number. It takes one optional parameter FFT size ( 1024 seems a good value). The way of doing it is to log power FFT input signal and then take the difference of the max and the mean values.

Quote from SV1BDS

Hi,

A GNURadio generic SNR calculation routine is built as an extended Python block. It takes a IQ data stream (usually a narrow one - a few kHz) and gives SNR as a real number. It takes one optional parameter FFT size ( 1024 seems a good value). The way of doing it is to log power FFT input signal and then take the difference of the max and the mean values.

Answer from GNURadio discussion email list

Hi,

A 10 MHz to 25 MHz converter using a 74HC390 as a /2 divider , a 4*xtal 25 MHz filter and a MAV11 amplifier at a designed PCB, produce about 8 dBm.

Quote from DC7KG

Hi George,

did you measure the phase noise?

Best regards,

Detlev

No, but using this method does not increase phase noise. I can measure phase noise but only when it is large. I evaluate it from the LNB performance in QO100. I used this method until now with good results. If you need more info please tell me.