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My shack
My Antennas
Leicester skyline

spectrum monitor

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One of the recent innovations that SDR radios have provided is the ability to display cluster/skimmer spots within the SDR Panadaptor. This facility is further advanced by logging programs which are able to customize the colour of displayed spots depending on various criteria. This is especially useful in contests where the spot can be used to indicate worked/multiplier status.

Regular readers will be aware of my contant battle with noise, both natural (QRN) and man-made (QRM) and some of my past attempts to mititage them. These include the purchase of a Wellbrook loop and both a WiMo QRM Eliminator and an MFJ-1026.

Both the WiMo and MFJ are quite capable at "nulling-out" noise sources but as one of my primary interests is 80m contesting, they just take too long to setup for each signal which really rules them out unfortunately. I had also mounted the Wellbrook on a cheap "TV" rotator but found that the nulls didn't seem to be deep enough for me to effectively remove the most persistent of noise sources that I encounter in my heavilly developed QTH. 

Sometime ago I became aware of Chavdar LZ1AQ and his designs for an active loop antenna amplifier (AAA-1) but what specifically interested me was the combination of multiple AAA-1 amplifiers with a variable delay line (VDL-1) which allows you to effectively steer the "array" with simple controls.  So I decided to purchase a VDL-1 and 3 x AAA-1 and see if I could build a steerable array.

One of the real benefits of an SDR based transceiver is that you get a visual representation of a portion of the band, or with some SDR transceivers you can view an entire band or bands if you wish. This is also in some ways a disadvantage as if you are in an urban area, you can see the enormous amount of man-made interference that is plaguing the bands.

In my professional life, I have been lucky enough to be involved with numerous projects and I was among the first people in the UK to import DVB-T modulators for HD video distribution. This led to installing HD distribution systems into a number of UK sports stadiums including the Leicester City Football Clubs King Power and Leicester Tigers Welford Road Stadiums. This allows clubs to retain their coax based distribution systems but replace the analogue modulators with high quality, low latency digital systems and sparked my interest in digital video.


I was then asked by Leicester Tigers to design a HD distribution and control system for their new 50m2 "big" screens that were being installed within the ground. They also wanted me to operate the screens on a match-day. This exposed me to a whole new world of HD-SDI video and involves regular discussions with broadcasters such as Sky Sports and BT Sport (I still enjoy my regular pre-match visit to the OB van to check that we are getting the correct feeds).


batcAs soon as I discovered D-ATV, I decided that this is something that I would like to try but I wasn't content to simply purchase a DTX-1 modulator from the BATC which is the common way to 'get on' D-ATV in the UK as that relies on a PAL analogue video feed and thought that I could do it better. The remainder of this article is my journey (so far) in this fascinating aspect of amateur radio.