USB & LSB on HF??
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USB & LSB on HF??
Could someone with some know-how pls explain the difference or significance of the USB and LSB on the HF radio. What or when can one or the other be used?
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In normal Amplitude Modulation (AM) signal generation a carrier and two side bands are produced. The side bands are designated Upper Side Band (USB) and Lower Side Band (LSB). It is actually not necessary to transmit all these signals to provide the receiver with enough information to reconstruct the original modulation, audio in this case. The carrier may be removed or attenuated, and so can one of the two sidebands. The resulting signals will require less transmitted power and will occupy less bandwidth.
USB is the norm for aeronautical HF communications, AM is used when a carrier is required such as while being checked for maintenance and as far as I am aware LSB is unused by acft.
USB is the norm for aeronautical HF communications, AM is used when a carrier is required such as while being checked for maintenance and as far as I am aware LSB is unused by acft.
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I left out the most intersting part, as Left Handed Rock Thrower has pointed out if the transmitters output power is used to transmit only a sideband, either one, the range is increased.
Thanks LHR.
Thanks LHR.
It never ceases to amaze me that people get to fly aircraft and are not instructed on all the equipment therein. Another case of an extremely poor reflection on instructors, training pilots and CASA.
HF like other equipment does need to be understood to obtain the max efficiency out of the equipment and the medium it uses. Too many, it seems, it is all to hard (and is left OFF) and only something that should be used on a rainy day, so you don't need to know much about it till then. Hopefully you will get lucky at the time you need it most!
Of course if you are under instruction you should have asked all these questions at the time?
HF like other equipment does need to be understood to obtain the max efficiency out of the equipment and the medium it uses. Too many, it seems, it is all to hard (and is left OFF) and only something that should be used on a rainy day, so you don't need to know much about it till then. Hopefully you will get lucky at the time you need it most!
Of course if you are under instruction you should have asked all these questions at the time?
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Gee Cogwheel I think you're being slightly harsh here. Other than avionic textbooks what other pilot material have you read this in?? I did a TAFE course and use a bit of Trevor Thom and it wasn't until I borrowed an Avionics textbook that I learnt about upper/lower sideband stuff, Amplitude Modulation, Frequency Modulation etc etc.
BTW no such this as a dumb question!!!! Better to ask now than later on!!!!
BTW no such this as a dumb question!!!! Better to ask now than later on!!!!
Sorry Scud, but don't agree. Have seen it far too many times when quite experienced pilots (Not just PPL's) fly aircraft that have an HF installed and don't have a clue on any HF basics or how to operate it. It is just assumed in many cases and I suspect not taught in others because the instructor/training pilot did not get taught either. How many pilots have you seen flying around with the squelch open and not knowing how to set it up?? And then they complain because of the noise they "have" to listen to all day.. Hello, anyone home!!??
A similar thing is going on with GPS. One is expected to know how to operate whatever is in the aeroplane. Sometimes it just aint that easy. (and you think the book is always in the aeroplane?)
Just another example of why the industry is going down the drain with such poor instructing standards. (and this is on the tip of the iceburg)
A similar thing is going on with GPS. One is expected to know how to operate whatever is in the aeroplane. Sometimes it just aint that easy. (and you think the book is always in the aeroplane?)
Just another example of why the industry is going down the drain with such poor instructing standards. (and this is on the tip of the iceburg)
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Loooxury.
This USB digitally tuned panoramic, vistavision, stereoscope HF.
When we were boy, had to wind out 150 ft of washing line aerial, tune little light thingy, select one of three fixed crystal locked every band, middle, upper and lower side band frequencies, look outside to see if it day or night, recheck correct day/night frequency selected, light wick thing for boiler to run steam generator, then, check to see if DCA FS had selected frequency on chart then talk.
Remember to wind washing line aerial back in before landing or replace 5/- (five shilling) plastic funnel drogue when you forgot and unwind 300 yds of fence from end of aerial.
Walk to PMG phone box make Airflash call to nearest DCA FSU to cancel SAR advised over HF??just to be sure.
Simple really.
As for these 95,000 freq synthesised wooser USB HF bah, not like them old days. <img src="frown.gif" border="0">
This USB digitally tuned panoramic, vistavision, stereoscope HF.
When we were boy, had to wind out 150 ft of washing line aerial, tune little light thingy, select one of three fixed crystal locked every band, middle, upper and lower side band frequencies, look outside to see if it day or night, recheck correct day/night frequency selected, light wick thing for boiler to run steam generator, then, check to see if DCA FS had selected frequency on chart then talk.
Remember to wind washing line aerial back in before landing or replace 5/- (five shilling) plastic funnel drogue when you forgot and unwind 300 yds of fence from end of aerial.
Walk to PMG phone box make Airflash call to nearest DCA FSU to cancel SAR advised over HF??just to be sure.
Simple really.
As for these 95,000 freq synthesised wooser USB HF bah, not like them old days. <img src="frown.gif" border="0">
I don't want to be the best pilot in the world - Just the oldest
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Cogwheel,
Perhaps the aircraft flown by pilots you refer to did not have HF fitted during their training. We have only one aircraft out of 16 on our line which does have a HF comm.
I know there a plenty of PPRuners here who are passionate about perceived falling standards in training. Without trying to make excuses, it is the regulator who decides the standards, not the training establishments. If more detailed theory training in this or other subjects was to be introduced into say the PPL syllabus then sure, areas such as basic radio theory and RF propagation could be covered. But then you would have organisations which advocate ideologies such as "freedom to fly without unnecessary restriction" crying out that the student is being taught information that is not required and incurring extra expense. It will do no good to provide the best theory training as part of a PPL course if the student decides he can achieve the same result cheaper elsewhere.
I seem to recall the briefing offices [RIP]used to produce an HF prediction chart to show the best frequencies for various regioins and times of day. Havent had a look to see if it is part of the available ASA briefing material but I bet it isn't.
[ 30 December 2001: Message edited by: Islander Jock ]</p>
Perhaps the aircraft flown by pilots you refer to did not have HF fitted during their training. We have only one aircraft out of 16 on our line which does have a HF comm.
I know there a plenty of PPRuners here who are passionate about perceived falling standards in training. Without trying to make excuses, it is the regulator who decides the standards, not the training establishments. If more detailed theory training in this or other subjects was to be introduced into say the PPL syllabus then sure, areas such as basic radio theory and RF propagation could be covered. But then you would have organisations which advocate ideologies such as "freedom to fly without unnecessary restriction" crying out that the student is being taught information that is not required and incurring extra expense. It will do no good to provide the best theory training as part of a PPL course if the student decides he can achieve the same result cheaper elsewhere.
I seem to recall the briefing offices [RIP]used to produce an HF prediction chart to show the best frequencies for various regioins and times of day. Havent had a look to see if it is part of the available ASA briefing material but I bet it isn't.
[ 30 December 2001: Message edited by: Islander Jock ]</p>
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CAT 1234 has provided the best explaination. Upper Sideband and Lower sideband operations are identical for operational purposes however. The reason that aviation uses USB is simply convention. Just as aviation uses the technically inferior AM for VHF comms, it's just a convention that cannot be changed.
The only services that use LSB are amateur and citizen radio services, so don't worry about them.
I think that this is a good question, and please dont be intimidated away from asking good questions here.
I don't know of any aviation radios that offer LSB as a user option, and knowing more than basic radio operation from a user perspective is unnecessary for pilots.
Even most avionics LAME's wouldn't know the answer to your question, and to this end CAT 1234 has surprised me.
The only services that use LSB are amateur and citizen radio services, so don't worry about them.
I think that this is a good question, and please dont be intimidated away from asking good questions here.
I don't know of any aviation radios that offer LSB as a user option, and knowing more than basic radio operation from a user perspective is unnecessary for pilots.
Even most avionics LAME's wouldn't know the answer to your question, and to this end CAT 1234 has surprised me.
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Cogwheel,
Although it's off topic, all GPS receivers that are fitted to aircraft are required to have a flight manual suppliment. If they don't either they are illegally installed, or the FMS is lost. it's the responsibility of the holder of the certificate of registration to ensure that it's all ok.
Regards,
PrUnIe
Although it's off topic, all GPS receivers that are fitted to aircraft are required to have a flight manual suppliment. If they don't either they are illegally installed, or the FMS is lost. it's the responsibility of the holder of the certificate of registration to ensure that it's all ok.
Regards,
PrUnIe
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prunehead
Don't forget that the MIL uses both upper and lower sidbands, which is easily switchable if you have Collins HF equipment on board. Some of the better MIL equipment actually used 4 independant sidebands, but then again, we weren't restricted to the normal 150w PEP that I think is a requirement for aeronautical mobile (ie. airplane). From memory, we used a very conservative 10kW per sideband (all four of them).
Fly_boy - general rule for HF - short distance between stns, use lower frequency; long distances, use higher frequencies. Pays to listen out on a few freqs first to see what is being used. Also if you are fitted with FSS (freq synthensised system) which allows selection in .1k steps, you can easily work the international frequencies - SP6, INO3, SEA3, PAC9, etc. although I don't recommend calling UJANG PADANG on 8MHz to cancel SAR somewhere in the middle of nowhere.
HF is akin to Morse code - another lost art, along with the Q and Z codes.
Don't forget that the MIL uses both upper and lower sidbands, which is easily switchable if you have Collins HF equipment on board. Some of the better MIL equipment actually used 4 independant sidebands, but then again, we weren't restricted to the normal 150w PEP that I think is a requirement for aeronautical mobile (ie. airplane). From memory, we used a very conservative 10kW per sideband (all four of them).
Fly_boy - general rule for HF - short distance between stns, use lower frequency; long distances, use higher frequencies. Pays to listen out on a few freqs first to see what is being used. Also if you are fitted with FSS (freq synthensised system) which allows selection in .1k steps, you can easily work the international frequencies - SP6, INO3, SEA3, PAC9, etc. although I don't recommend calling UJANG PADANG on 8MHz to cancel SAR somewhere in the middle of nowhere.
HF is akin to Morse code - another lost art, along with the Q and Z codes.
The Amateur Radio service used LSB under 10 Mhz (3.5 and 7.0 Mhz band allocations) and USB above 10 Mhz (14.0, 21.0 and 28.0 Mhz band allocations). CW is used in the lower section of each band allocation.
Above 30 Mhz FM is generally used.
HF range = 3 to 30 Mhz
VHF range = 30 to 300 Mhz
The Wireless Institute of Australia <a href="http://www.wia.org.au/" target="_blank">http://www.wia.org.au/</a> have some excellent training material available on RF propogation.
ARS: VK4VEE
[ 30 December 2001: Message edited by: Torres ]</p>
Above 30 Mhz FM is generally used.
HF range = 3 to 30 Mhz
VHF range = 30 to 300 Mhz
The Wireless Institute of Australia <a href="http://www.wia.org.au/" target="_blank">http://www.wia.org.au/</a> have some excellent training material available on RF propogation.
ARS: VK4VEE
[ 30 December 2001: Message edited by: Torres ]</p>
Gee Gaunty, you are obviously old enough to know that a "cat's whisker" is neither a protuberance from a feline head, nor a measurement of fine tolerance, but indeed a term relating to wireless.....
