In my latest LF Receiver project, I use a 9850 DDS clocked from a low phase noise 10MHz source, to directly generate the LO of 455 to 605kHz for mixing 0 - 150 up to 455kHz IF. The DDS filter is a cu
From Alan G3NYK us lesser mortals it is barely adequate. I was also quite taken aback by the "chunder" that could be heard with no signal at 136k, this is probably the PLL reference. It is something
In an attempt to reduce the problems associated with modern Radio Communications, the following legislation needs to be introduced -- The recently discovered decreasing value for the speed of light n
Off topic I know, but I crave your indulgence :-) Looking at the specifications for the IC8500 Communications receiver, I notice that for the US market the bands 824 - 849 and 867 - 894 are blocked -
Well, I'm already talking at the HF Convention on Digital Voice and related topics, but could give an off-the-cuff overview of the Tx. Say about 15 - 20 minutes........... Could be a busy day ! Andy
Just a thought .. Place any small LF antenna located on very dry, low conductivity ground such as desert or non conductive rock with no trees etc nearby. With a good groundplane installed of thick co
I will use the 'fat' coil formula because with my coil D = 60cm and H = 18.2cm I don't understand the L^2 in the formula because L is what I am trying to find. A misprint for N, which doesn't appear
A search tree such as that suggested would generally be used for searching multiple complex inter-related data. For the small set of symbols covered here here, a direct addressed parallel memory base
Turn the question round a bit and think outside our amateur radio world... Why do the Canadian Navy need to transmit on 137kHz ? What does a broadcast on this frequency offer that either HF or satell
Was alerted to this at 2150a by G0API and drove out to a darker area of countryside to look. Impressives slowly moving dark red patches in the northern sky that obliterated part of the Great Bear con
There are also still many of us on LF, fortunately, whose interest is in the science and technology of radio communication, rather than merely having QSOs. Repeaters such as this reflect the true spi
I'm glad this subject has cropped up, even if off topic of LF. Two years ago, when the Leonids shower was going to be particularly good in the UK, with clear skies, I went out meteor spotting in the
Read the article on Dopplergrams by G3PLX in RadCom three or four years ago ... There is likely to be several Hz of Doppler shift on that frequency at night time. Guess who forgot that simple fact la
I saw nothing, but may have gone for too narrow a bandwidth on the monitoring system - Argo in this case - and missed the signal. What was the frequency ? QRSS would be an interesting way for those o
Does anyone know of a chip that does the following function : A serially loaded high-sided driver several outputs, with outpult voltage rating greater than 15V and current > 100mA. The sort of functi
What's your locator, or preferably NGR, Laurie, and your eight/ten digit locator (or Lat / Long ) if you have it John Andy -- This of course must be an amateur distance record for 73kHz can anyone wo
If you use a larger capacitance resonance will naturally be at a lower frequency so you will be measuring the Q there instead. Selectivity will be higher, but when the bandwidth at the 3dB points is
For the weighting elements why not use a binary switched attenuator. At low frequencies, FET switches onto a tapped constant impedance resistor ladder will give you constant impedance and exact atten
In the UK the standard capacitor is 1.8uF and maximum ringing load is 1000 ohms (REN = 4) based on old legacy system. The actual ringing voltage is 'spiky' at a PRF of 25 Hz. I'll have a look at its
Same in the UK. Ring voltage is a low frequency bipolar spike waveform of a 100V or so amplitude, Originally designed to hit the bells firmly, the waveform seems to have been kept for legacy reasons.
