---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Sat 07/27/19: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:25 AM - Re: Frequencies and 8.33 Channel numbers (Kelvin Weston) 2. 09:02 AM - Re: Frequencies and 8.33 Channel numbers (JonathanMilbank) ________________________________ Message 1 _____________________________________ Time: 02:25:13 AM PST US Subject: Europa-List: Re: Frequencies and 8.33 Channel numbers From: "Kelvin Weston" Hi Jonathan Most low-end GA radios require you to select either 8.33 or 25Khz mode in the setup and will only display the associated channels or frequencies for that bandwidth. If you have a radio that allows you to select both channels and frequencies directly using the frequency select knob, then it may well adjust the bandwidth automatically. Whichever mode you are in, selecting a frequency of 134.1 in 25 Khz mode or channel 134.105 in 8.33 mode will use the same carrier frequency of 134.1 Mhz for transmit and receive. However due to the differing bandwidths, a 25 Khz station should be able to receive your transmission ok but an 8.33 station (your aircraft) may not receive a 25 Khz transmission as clearly. This can be due to a number of factors concerning radio wave propagation, transmission, etc. and is a known issue. See the 2nd to last paragraph of this article issued by Eurocontrol: https://833radio.com/news/show/7 There are lots of similar articles on the web. Unless you wish to change radio, your current method is probably the best way to achieve satisfactory comms with regularly used 25 Khz stations. -------- Regards Kelv Weston Kit 497 kelv@kdweston.biz Read this topic online here: http://forums.matronics.com/viewtopic.php?p=490549#490549 ________________________________ Message 2 _____________________________________ Time: 09:02:50 AM PST US Subject: Europa-List: Re: Frequencies and 8.33 Channel numbers From: "JonathanMilbank" Thanks Kelvin. An interesting article. Another factor re Aberdeen Offshore Radar 134.1 MHz occurs to me, viz some years before the introduction of 8.33 KHz channel spacings, Aberdeen had already introduced rebro for offshore helicopter communication purposes and thus three additional remote transmitters were placed on offshore platforms over 100 miles apart. This also involved telephone links to the remote transmitters and synchronisation problems were challenging. >From what I think I was told, the 25 KHz band segment assigned to 134.1 MHz was subdivided into 4 of about 6 KHz each (I guess) and so the transmissions had very narrow bandwidth but the receivers remained capable of the full 25 KHz. At least this is what I vaguely recall from my days of flying helicopters to North Sea destinations. There were "black holes" in the coverage offshore. I wonder if the difference between 8.33 KHz bandwidth of my aircraft radio and the presumed 6.25 KHz of the rebro system causes some "mismatching" effects, when my radio is erroneously selected to channel 134.105? Any polite suggestions welcome! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=490553#490553 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/europa-list Browse Digests http://www.matronics.com/digest/europa-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.