Hi Dave, At 10:46 AM 8/28/2006, you wrote:
>I have reviewed enough of the military documentation to understand >that they employ dedicated ALE transceivers capable of much faster >scanning rates. Really? Please enlighten me, I was under the impression that the ALE scan rates of 1, 2 and 5 ch/sec was it at present and that the future goal as stated in MIL-STD-188-141B was 10 ch/sec. The PC-ALE software supports 1, 2 and 5 ch/sec with an HF transceiver that is cable of all selections. > As a result, sounding duration is signficantly >reduced, Sorry, but you will have to explain to me how Sounding duration decreases with an increase in the Scan Rate. > and channel capacity increases in proportion. Well not exactly. A 2 ch/sec scan rate allows you to cover the same number of channels faster than a 1 ch/sec scan rate and thus increase the odds of hearing a Sounding or a Linking call sooner. Running 2 or 5 ch/sec will also permit the station to be part of more than one ALE network at the same time, not an issue per see with Amateur Radio, but if two networks had scan groups of 10 channels each, you could scan both with excellent results. The number of channels you scan does have an effect on your Soundings, you sound longer when you have more channels in the mix. There are variable here as we are now at a stage were you have 3 generations of ALE. The latest ALE technology supports GPS time synchronization of the Scanning/Sounding which in the future will radically reduce BER/SNR data transfer for LQA ranking when all user's can support it. > But one ham >with an amateur transceiver limited to a 2 channel-per-second scan >rate would force all ALE participants to sound for 20 seconds, even >if their equipment could scan more rapidly. Do I have this right? The details are to be found in MIL-STD-188-141B Appendix A. Regardless of the scan rate, if the controller Sounds based on number of channels in the scan group its less than 1 second per channel. The minimum redundant sound length (Trs) is equal to the standard one-word address leading call; that is, Trs = Tlc min = 2 Ta min = 2 Trw = 784 ms. Thus for 12 channels it would be about 9.4 seconds depending on your address length being sent. The address length is based on an ALE Word which is 3 ASCII characters, for Amateur Radio applications we would being using 2 ALE Words as there are no 3 character callsigns, whereas in the Military and Government world there are 3 character ALE Self Addresses being used. So W1AW, N2CKH and WB2XYZ are all 2 ALE Words were automatic padding is used to fill the second word. The least number of ALE Words the more efficient and reliable is the system. One would now want to use WB2XYZ/W6 to indicate they are in California. For AQC-ALE where many things were changed to make things even more efficient, a 2 ALE Word is the maximum allowed, whereas the original ALE allowed a 5 ALE Word (15 character) Address to support the Military Automatic Digital Network (AUTODIN) system to directly link a Phone Patch call. Feel free to double check me with the standards, I am no expert on all this stuff and I am not perfect either, I make calculation errors often. /s/ Steve, N2CKH Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
