2021-11 Scottish Microwave Round Table - GMRT - postponed to 2022
Taking a leaf from the Olympics book - the 2021 GMRT unfortunately won't be able to go ahead, but there's every intention of it running in 2022.
It's not just Covid; the Museum of Communication lecture area is undergoing a major roof replacement, and the venue is unlikely to be useable by November 2021.
It is anticipated that this year Covid would impact the numbers attending; we need at least 40 people to make the event viable at £10 per head. In addition, Covid is likely to impact the ability to secure speakers who are willing to travel to the event, so setting up a suitable programme would be a major challenge.
We really do hope to see the event happening in 2022, and look forward to seeing you there.
- John GM8OTI.
2021-10-24 Galashiels Rally Cancelled.
2021-10-09 MOC Goudie Lecture:
2021-10-02 WSPR may aid search or missing MH370 airliner.
2021-09-25 - Poles cracked Enigma Code first.
Photo courtesy BBC News.
2021-09-16 - Lunar Pathfinder - the first UK satellite to go to the Moon in 2024. Tnx Colin GM4HWO.
Lunar Pathfinder.
2021-09-11 MOC Goudie Lecture Quintinshill 1915 by David W Brown. (Zoom).
2021-08-02 Quantum: Flagship UK telecoms satellite launches. (Tnx Colin GM4HWO).
2021-07-18 B2 Spy Set, BBC Antiques Roadshow. Estimated value £10,000 to £15,000.
Click to view (go to about 52mins). Courtesy BBC.
2021-07-17 MoC Goudie Zoom Lecture Star-Gazing with Stephen Hawking by Prof. Joe McGeough, University of Edinburgh.
2021-07-14 Noctilucent Clouds by Peter GM4DTH.
2021-07-04 SAQ Annual Alexanderson Day Transmission on 17.2kHz
Not bad for 17.2kHz !
2021-07-01 GM6SR's Top-Band Crystal (click for full SK article.
2021-06-23
Yes, we've given up CW here.
2021-06-19 MoC Goudie Lecture The Fishwives of Fisherrow by Simon Fairnie of Musselburgh Museum.
2021-06-09 Barnton Quarry Nuclear Bunker given Category A Listed Building Status.
Photo courtesy EEN.
2021-05-23 - RSGB Videos on YouTube.
2021-05-23 RSGB video: 2020, a year like no other.
2021-05-22 Sunspot causes blackouts up to 20MHz.
2021-05-21 Scientists find source of Fast Radio Bursts (FRBs) being sent to earth.
2021-05-15 MOC Goudie Lecture by Prof.C. Withers - Mapping Scotland's Islands.
..........................................................................
2021-05-10 NASA spacecraft hears ‘hum’ outside our solar system.
2021-05-04 Military Morse code experience helps elderly couple bust out of assisted living facility!
2021-04-30 New 6m Beacon GB3RMK at Rosemarkie, installed by Brian GM8BJF of LRS. The beacon is now back on the air on new frequency of 50.460MHz, running 80mW QRP. It idents on FSK, CW & PI4. Chris GM3WOJ is looking for a low-band base station suitable for conversion as a PA. Reports and spots appreciated. "We were up at the site (in the snow) installing this morning. It is well placed to the south".
2021-04-25 2m Repeater GB3AG near Dundee - temporarily closed due to Silent Key of keeper Peter Carnegie GM1CMF. Back on in one week with new keeper Garry Bertie MM0XET.
2021-04-23 Pink Noise Generator Project for RSGB GB2RS Transmissions - Peter GM4DTH.
Completed Pink Noise Generator board.
As you know I can be rather critical when it comes to audio quality. I am concentrating on local communications with relatively high signal strengths. Weak dx signals are a different case and require a different approach.
In this case I am looking to improve the quality of my own transmission when providing the news service. For reasons unknown the audio quality from equipment using NBFM designed for the radio amateur market rarely matches equipment used in commercial service. I suspect that there is no consistency with handling the output from a microphone. I would expect some frequency tailoring and a degree of signal compression followed by pre-emphasis to modulate the transmitter. The receive path should have matching de-emphasis and quality audio circuitry. The amateur equipment is made for a global market and I suspect that may play a role in the disappointing audio. Many users seem happy to listen with a tiny loudspeaker that has remain unchanged since they were introduced in 1960’s 6 transistor portable radios powered by flying bomb batteries. Listening to pre and post news calls reveals a wide range of audio quality with a substantial number falling into the poor category. It is often the older equipment that sounds better. Leaving CTCSS on when not needed further degrades the audio.
I have never been satisfied with the transmit audio from the Yaesu FT736 I use for the news. Its microphone path to the modulation stage colours the audio in a manner I dislike. There is a port designed for data use which bypasses all the modulation audio stages and I have been using that. One has to be careful with levels as there is no limiter or any other processing or protection when using that port.
This whole process was triggered after I recorded the news transmission from the new station in the borders and with it my own audio recovered from a Marconi modulation meter (flat response no de-emphasis). When checking the recording I thought I would apply quick and dirty de-emphasis using the audio editing software. The audio then sounded rather good. Looking at the correction curve I felt that it was wrong. I suspect that the data port I was using may actually be phase modulating rather than frequency modulating. I do have the correct pre-emphasis applied for FM but it will be wrong for PM.
At this point I thought it may be best to start again. This is where the pink noise generator will play a role. There are two ways of checking the transmission audio. The best is to use an audio spectrum analyser and a tracking generator and look at the actual response. I do not have that combination. Passing noise through the system will also reveal the response. It is the poor mans approach but it should work. I am only interested in frequency and amplitude response I am not interested in its phase characteristics.
My plan is to feed the noise via an equalisation network to the ‘data’ port which should allow me to approach the ideal response. I hope that will allow me to maximise the audio quality.
Before the equalisation, the audio is passed through a compressor to gently lift the talk power then onto a limiter which should do nothing unless the audio is overdriven. I use Peak Programme Meters (PPM) to watch the levels. 4 on the meter gives 50% modulation (1.2kHz deviation) and 6 gives 100% modulation (2.4kHz deviation). Anything over 6 triggers the limiter. (I have attached tow photos one showing the source mixer PPM with the test tone on the other is the equipment programme meter) Note that I do not use 2.5kHz as a maximum, this is to allow a greater degree of frequency error in receivers assuming they have correct IF filters installed. The last time I checked the transmitter frequency it was off by 24Hz and seems to be relatively stable. I have not carried out a long term assessment.
- Peter Dick GM4DTH
.....................................................................................
..........................................................................................
2021-04-17 MOC Goudie Lecture by Roy Johnstone - TV Programmes we used to watch.
.........................................................................................................
2021-04-13 Titanic Radio Operator's post-card for sale
.........................................................................................................
2021-04-02 - Silent Key - Samuel Morse, on this date in 1872.
.........................................................................................................
........................................................................................................
2021-03-31 144 MHz VHF May Contest 2021: LRS Contest Group GM3HAM is planning to go out on weekend 14-15-16 May 2021. A field has been booked for that weekend at Gatehouse of Fleet - camping on site. 6 attendees so far. We are looking for people to attend especially to set up and dismantle the site. Contact Colin GM4HWO or via the GM3HAM reflector.
..........................................................................................................
2021-03-20 Cockenzie & Port Seton Mini-Rally on 13 Aug Cancelled.
.........................................................................................................
2021-03-16 How long will an electric car’s battery last? (It depends)!
Photo courtesy wikipedia.com
........................................................................................................
2021-03-15 "HAMS" - film of Aberdeen ARS in 1961.
......................................................................................................
2021-03-13 MOC Goudie Lecture by Mike Bullock - The Northern Lighthouse Board - More than Lighthouses.
.......................................................................................................
2021-03-12 Union Chain Bridge - now under repair. (Subject of LRS talk on 25 Sept 2019). (Click).
..................................................................................
2021-03-05 Sinclair ZX81 made in Dundee turns 40.
........................................................................................
2021-03-03 IARU EMC Software: recommended by Norrie GM1CNH re new OfCom regulations.
...................................................................................
2021-02-20 MOC Goudie Lecture by Prof. Tom Stevenson: Orkney - Energy Islands.
..........................................................................................................
2021-02-17 Ham Radio signal from Chinese Mars spacecraft recorded by Scott Tilley VA7TIL.
.......................................................................................
2021-02-11 RF Line-of-Sight Tool (SCADACore) (Tnx GM4DIJ)
.......................................................................................
2021-02-06-08 AM Rally (HF+6m), tnx Mike GM8KCS
See: AM Rally Homepage for full info.
..................................................................................
2021-02-06 New Short RSGB Video: Did You Know?
.......................................................................................
2021-02-01 Titanic Radio Room Retrieval scrapped.
......................................................................................
2021-01-25 "Rutherglen BAOR Officer on Air to Home" - Lieut. Roy Dawson, later-GM3GBX.
..................................................................................
2021-01-24 Elon Musk SpaceX launches record 143 satellites in one mission.
....................................................................................
2021-01-21 George Szymanski in the Philippines
DU1GM/GM4COK wants to hear from you!
Former LRS member George in the Philippines would love to hear from any members who remember him.
See: DU1GM (dxhams.com)
See: LRS Archive (scroll down to callsign).
...................................................................................
2021-01-17 WWI Secret Listeners video BBC
.................................................................................
2021-01-12 Lecture "The Demise of Ferranti" by Prof. John Wilson - now on YouTube (click).
.................................................................