Noise power is proportional to bandwidth At room temperature, a resistor will develop -174dBm of thermal noise or -174dBm/Hz In a 2.5kHz SSB bandwidth, the total power is therefore -174 + 10.LOG(25
The linearly biassed gates used to buffer the input of the Softrock LO fail at low frequencies, breaking up into spurious oscillations at the threshold changeover, not operating the divider properly
Looking at the schematic, I see a 74AC74 divider is used which works at over 100MHz clock frequency. You are hitting its edge triggered clock inputs with low frequency waveform (461kHz) with a slo
a proper shaped logic level to such high speed divider chips. There really is no getting round that fact. They won't work properly otherwise - just look at the specifications for AC series logic.
Is a simple design sampling to 10 bit resolution at 80kS/s or 62.5kS/s with embedded timestamp of any interest? I have one based on a 16F688 PIC and RS422 interface running at 2M baud. At the PC en
If you only have supply of 0/5V you cannot have a negative '0' level. If your scope shows it, then it is possible your scope ground is not connected properly yo the -ve rail but instead to somehti
My 700 Watt design could probably be increased to over 1kW now with more modern components. Take a look at http://www.g4jnt.com/137tx.pdf Andy G4JNT On 8 February 2018 at 18:34, <g3kevmal@talktalk
After reading this, I installed WSPR-X on my new Win-10 notebook. It didn't work in "normal" mode. But when modified to run in XP compatibilty mode, worked fine. I ran it in parallel with WSJT-X fo
Can this really be the same Mal who, just 20 years ago, called anyone who used a computer on the LF bands and didn't operate a straight key at 30 million WPM an 'Appliance operator' ? How times chan
On my wall calendar, against 16 March through to 21 March, I have written "start topband beacon". Not sure what this was about, but I do vaguely recall a mention of Greyline and things a few months a
Glad I started testing the 1.8MHz WSPR bcn today Several of us appear to have made it to Antarctica 2018-03-13 05:30 K9PAW 1.838190 -30 0 EN61ar 1 DP0GVN IB59uh 13980 156 2018-0
After, definitely Before is applicable to VHF and up where equipment noise figure dominates sensitivity and a filter in the antenna side wold add loss and degrade overall NF At HF and certainly LF, a
Perhaps too high a freq for this group, but whatever ... Topband used to be called "LF" As some discussions here a few months ago suggested, propagation to VK on 160m may be good at this time of ye
Looking at some large pot cores , I was struck by this novel idea. Back in the very early days of 10GHz with wideband equipment, we tuned Gunn oscillator using a dielectric probe on a micrometer head
Hello Andy, do you mean something like this: http://www.wireless.org.uk/dk5pt-f.htm ? 73, Rik ON7YD - OR7T Van: [email protected] <[email protected]> namens Andy Talbot
73! Alex R7NT 136.73.ru 2018-03-23 15:38 GMT+03:00 N1BUG <[email protected]>: LF / 2200 meter community, I am a little afraid to ask this question. I don't want to start a "war" here. But... What is th
I made a custom LF receiver and digitiser, then send the I/Q sampled at 1kHz to the PC on an RS422 interface. It's described here http://www.g4jnt.com/Coherent_LF_Receiver.pdf As the sampling is at 1
WSPR beacon on overnight - it's been running from mid afternoon. EIRP around 200mW, but may be a bit less as the ground is so wet. To add a bit of variety, the PIC + DDS source now has randomised f
