Thursday, 30 September 2010
It has been a few weeks since I dug out my neglected scanners and despite not being able to spend hours with them I have still had an enjoyable time reacquainting myself with them and experimenting.
Despite the growing use of digital transmission systems there is still a lot to listen to on the airwaves. I should note at this point that using a scanner to monitor anything that is not intended for 'General Reception' is illegal.
The Amateur bands are fairly quite around my location, however I was pleasantly surprised to be able to here to receive a number of Amateur repeaters both on the 2 meter and 70cm bands despite appearing to be outside the predicated coverage.
The CB bands are also very quiet but I suspect that is more to do with the high levels of interference I seem to be suffering. I have been struck by the apparent increase in interference (QRM) on a lot of the bands since I last used the receivers. I can hardly hear anything on the short wave HF bands except the more powerful commercial transmitters.
I suspect this interference is down to the proliferation of computers and associated peripherals, wired and wireless networking. Energy saving fluorescent lamps and microprocessor system in all manner of consumer equipment such as TVs, PVRs, DVD players for example means the airwaves are full of noise.
The Radio Society of Great Britain (RSGB) who represent the thousands of Amateur radio operators have begun to campaign to save the radio spectrum from such interference, specifically they are currently campaigning against the threat poised by the proliferation of PLA/PLT devices (such as HomePlug) these devices use the house mains wiring to transmit network data. However what happens is the wiring then acts an effective radio antenna transmitting the traffic at such levels blocking out other legitimate radio transmissions. This sounds(sic) to be in direct contravention of the EMC Directive of the EU that prohibits the manufacturer of any device that interfers with radio and telecommunications equipment.
However despite representations by the RSGB, the BBC and others OFCOM and the last Government have dragged their heals and refused to act. Hopefully the new Collation Government will be different, but I won't hold my breath. More information at UKQRM
However given all this noise there are still things to listen to, of course I haven't since it is illegal, but if I were so inclined there are plenty of analogue VHF/UHF Private Mobile Radio (PMR) systems still being used by commerical organisations. Such as taxi firms, councils, security patrols or by large business to facilitate communication across sites.
In the past it would be difficult to know the source of the transmission often listening for clues to try help identify them such as names of locations, buildings, streets and people for example. However nowadays it has been made a little easier by OFCOM who have allowed on-line access to the Wireless Telegraphy Register database. The use and allocation of radio frequencies is strictly regulated so now if get a hit on a frequency it is possible to use the WRT website to help identify them.
The air and marine bands are still as active as ever, given my location near to a number of RAF bases it could prove interesting if I were also so inclined.
Wednesday, 15 September 2010
I have just successfully bid on ebay for a copy of The Ladybird Book - The Story of The Radio I was browsing earlier and stumbled across Tony Ling's website and it features an altered picture of the front cover and it sparked some nostalgia.
This was a book I was given as a child and remember being enthralled by its contents. As the blurb says the book tells the fascinating story of radio, from the early forecasts of James Clerk Maxwell and the experiments of Heinrich Hertz and Marconi to the modern Post Office Tower (remember it was first printed in 1968) and the use of radar.
Just got to wait for delivery...
I might go looking for a copy of the 1972 Making a Transistor Radio and might actually have a go at building one, but there are some pitfalls in it's design!
Monday, 13 September 2010
Ever since I was old enough to handle a screwdriver and a soldering iron I have had an interest in radio communications and electronics. I spent many a hour in my childhood scanning the Medium and Short Wave bands with various receivers (usually scavenged from family, neighbours or saved from the dump!) I constructed numerous long-wire and other bizarre antennas. I even did a presentation on my hobby for my English Language O-Level exam - I really did confirm my status as a weirdo!
I played with borrowed CB radios and would have loved to progressed into owning one or becoming a proper radio amateur but unfortunately I simply didn't have the money.
Then the home computer revolution started and my Dragon32 and Tatung Einstein took up most of my time. I left school and went off to University and when I came back home and got a job I spent some of my money on a new fangled radio scanner, a Realistic PRO2022 from Tandy.
A scanner is a radio that covers a wide frequency range, they are controlled my microprocessors and allowing you to listen in to a huge range of different communications including air traffic control, hobbyists (Citizens Band, Amateur radio), security guards, taxi's and a lot more. Back in the late 80s, and early 90s they also allowed access to the emergency services and the old analogue cellular phones! Connecting it up a computer and using some software you even decode pager messages!
Gradually all the 'fun' stuff disappeared, the mobile phones became digital, so did the emergency services. This along with other commitments, such as moving across the country to a new job, getting married and other demands on my time meant the scanner ended up collecting dust in the attic.
Several years ago I briefly dusted it off and brought a couple of other second hand scanners including a Realistic PRO2006 and a brand new Alinco-DJ3X. I also played around with some PMR446 systems, but sadly again they all ended up collecting dust.
Well once again they are out of the boxes and I am having a fun time scanning around for interesting signals, well if you can count listening to the radio microphone at a local church interesting!
I am thinking of buying a CB as it seems to have evolved from the bad old days into something more grown up. Even becoming a DX amateur type system using something called freebanding not legal mind, but then technically using a scanner isn't!
I am even contemplating taking the Radio Amateur exams and actually achieving a childhood dream, well I do now have access to money and did do an electronics degree!
This time I hope it doesn't all fizzle out and it is looking more promising as plans are a foot for me to have my own shack and I won't be spending as much time on my other hobbies next year.