MY QO100 SETUP

Quote from SWL-Waleed

500 Khz
Also changing the TX gain plays video for another 20-25 seconds

I have no idea. Usually for 500 KHz bw with 2 KHz accuracy you are ok. I have use a TCXO based receiver. May be yours shifts with time. We must not forget that DVB-T was designed for 5-8 MHz bandwidth !!!

Quote from SWL-Waleed

Does this accuracy decreases as Bandwidth increases? if that is the case i will increase the bandwidth!
my data rate is 450-600Kbps!
I have a GPSDO, where should it be placed with, either with reciever or transmitter?

We use 2K mode with 1705 sub carriers - dividing bw by 1705 gives an indication of accuracy required. A GPSDO will solve frequency stability problems. It can be used at either side or better both. If used both sides the offset must be 0 !!!

Hi,

The telemetry sub project was improved adding PTT reading and 10 sec power reset of the Pluto as when Ethernet disconnected only cycling power is return it to be alive.

Hi,

A new version is uploaded. RIT is reversed again. An improvement was added.About delay I have not measure it.

Quote from SWL-Waleed

What are the ways to secure the DVB-T stream, for example how scrambling is done? or if can be encrypted using AES or RSA?

Hi, this is outside hamradio.

Hi,

Just another 8 way splitter for 25 MHz. It can be used also for 10 MHz.

Hi,

As the 8 way 25 MHz splitter has more attenuation than permitted to work efficient the driven elements, a MAV11 12 dB amplifier is put before it. Updated block diagram.

Hi,

A SI5351 lab generator is build using eBay ready PCB and a Arduino nano. Xtal is removed and clock is feeded from external GPSDO based 25 MHz reference. So 2 outputs can provided with GPSDO based accuracy and stability. A decoupling capacitor is required at output if feeded to 50 ohm load. Software is build from SV1EED and the pair of frequencies can saved if desired. A 7808 provides power independently from USB.

Hi,

A pair of DC block SMA adapters was built for SI5351 outputs. A pair of parallel connected 1uF+1nF capacitors was used in order to pass all the frequencies. An unsoldered PCB is also shown.

Hi Matthias DD1US ,

Thanks for your note, I measure S21 now and from 10 KHz to 500 MHz is flat 0 dB loss. No resonance exist. I use 0805 for both of them. The required response is 8KHz to 160MHz. This must be true for a non SMD one.

Thanks again !!!

S21 from 50MHz to 20GHz.

Hi,

Anyone have used this B210 clone?

Link

Hi,

A HF signal monitoring system is build for research usage. This project idea can be used, if desired, to daily monitor QO100 NB & WB activity and usage. Statistics also can be calculated.

An active antenna (LA8AK circuit) with a 1m whip can receive 10 KHz-30 MHz. A 4 way splitter provide the signal among others to a USRP1 SDR with a 0-30MHz Rx card. The USRP1 is connected to a i5 1.6 GHz low consumption PC with a 4TB HD and a 60 GB SSD for Ubuntu 18.04. The PC runs at about 50% CPU. A GNURadio generated Python script runs every 2 min for 100 seconds. It has 16 bit 6.4 MHz sampling rate, so the same RF bandwidth received. Three frequencies ranges are covered (1.6-20.8 MHz total covered frequency range). The frequency selection criteria was that this range is relative non infected from local interference. If it is installed in a better environment all the 30 MHz range can be easy covered. So every cycle it takes 6 minutes and then is repeated.

Two 1024 FFT points run, one 100 per second and the other one once a minute. This gives 6.25 KHz resolution bandwidth per FFT point. The minimum signals is -150 dBm and the maximum is -150+128=-22 dBm (dynamic range 128 dB). A resolution of 0.5 dB is archived. Data are saved in two category files. The low resolution is saved in 3 daily produced files, one per frequency range. The high resolution is saved once per 100 seconds (3 files per 6 minutes). The high resolution produced files are 7.2 GB per day, giving hundred of days storage capability. The creation of files is automated with cronjob entries. Only delete is not automated as manual activity is desired.

To visualise the recorded data three possible images files can be produced. All of them are spectrograms with X axis the frequency, Y axis the time and colour the received signal strength in dBm. A colour bar with dBm values exists also. The produced .PNG files are : 100 sec high resolution data files, the 6.4 MHz wide daily data files and the 3 frequency ranges combined daily file. The combined and the 3 daily image files are auto produced daily. Sample outputs are attached. Time is local UTC+2. It can easy noticed in the combined file, the usage at broadcasts bands.

Ideas for new features and improvements are welcome, some of existing ones are:

- video animation of daily image (combined) files

- IQ data storage on trigger event

It is examined that daily combined image files will be available via my site.