FAA Plans to Change to Radios with 8.33 MHz spacing?

The satellite ain't goin' 17,000 mph with respect to the ground station.
Doppler will be small with short transmissions.


"Bill D" wrote in message
...
On Saturday, April 13, 2013 12:26:36 PM UTC-6, Bear wrote:
Bob,



I don't believe that we switch to GSM or whatever.



1. For none of the digital communication techniques it was possible to

find a global frequency range.



2. The relative speed is too high. To my knowledge the highest speed to

which a digital communication system is certified is 500 km/h (310 mph).

This is GSM-R, Global System for Mobile Communications - Railway or

GSM-Railway, for details see Wikipedia.

500km/h would be good enough for us but not for others. We can forget it

in aviation thanks to Doppler effect.



Bear

So, how is digital communication with 17,000 mph satellites possible with
Doppler effects?

Nobody suggested GSM as an alternative to a global aviation-specific
digital communications protocol.

In article Bear writes:
Bob,

I don't believe that we switch to GSM or whatever.

1. For none of the digital communication techniques it was possible to
find a global frequency range.

Seems unlikely. Are you saying that there is no VHF or UHF band available
worldwide?


2. The relative speed is too high. To my knowledge the highest speed to
which a digital communication system is certified is 500 km/h (310 mph).
This is GSM-R, Global System for Mobile Communications - Railway or
GSM-Railway, for details see Wikipedia.
500km/h would be good enough for us but not for others. We can forget it
in aviation thanks to Doppler effect.

Bear

Hmmm. The prime communications channels with the space station are digital.

DirecTV and Dish Network are digital. The network feeds to your TV stations
are digital via satellite. The "cable channels" are fed digitally to your
cable companies.

GPS is digital. It seems to be popular in aircraft.

Alan

The present 2-meter AM air-band "Party line" originated as a military system in the biplane era. Today's military has many highly secure digital communication nets used for airborne operations from close air support to drone attacks.

The DOD likes the idea of using COTS products so wherever possible, they push military technology into the commercial domain to spread R&D costs and reduce the price they pay per unit. That's where the air-band replacement will come from.

Why would the FAA and ICAO want to do this? Bandwidth. Digital communication uses spectrum far more efficiently and it eliminates channel clutter so pilots hear just what they need to hear.

On Saturday, April 13, 2013 2:13:33 PM UTC-6, Bear wrote:
What is your proposal?





So, how is digital communication with 17,000 mph satellites possible with Doppler effects?



Nobody suggested GSM as an alternative to a global aviation-specific digital communications protocol.

http://en.wikipedia.org/wiki/Orthogo...n_multiplexing

From wikipedia:

Summary of advantages
*High spectral efficiency as compared to other double sideband modulation schemes, spread spectrum, etc.
*Can easily adapt to severe channel conditions without complex time-domain equalization.
*Robust against narrow-band co-channel interference.
*Robust against intersymbol interference (ISI) and fading caused by multipath propagation.
*Efficient implementation using Fast Fourier Transform (FFT).
*Low sensitivity to time synchronization errors.
*Tuned sub-channel receiver filters are not required (unlike conventional FDM).
*Facilitates single frequency networks (SFNs); i.e., transmitter macrodiversity.


On Saturday, April 13, 2013 1:13:33 PM UTC-7, Bear wrote:
What is your proposal?





So, how is digital communication with 17,000 mph satellites possible with Doppler effects?



Nobody suggested GSM as an alternative to a global aviation-specific digital communications protocol.

On Thursday, April 11, 2013 2:33:51 PM UTC-7, Paul Remde wrote:
Hi,



I imagine someone on this newsgroup can point me in the right direction on a

technical/FAA question.



Becker offers 2 versions of their AR6201 radio. The original version has

frequency spacing that can be set to either 25 mHz or 8.33 mHz. The new,

slightly lower cost option has frequency spacing fixed at 25 MHz It is my

understanding that the 8.33 MHz spacing is required in Europe, but not

currently in the USA. Customers are asking me whether the FAA has any plans

to go to the 8.33 MHz spacing in the near future - so they can be better

equipped to select the radio version that makes sense. At a recent soaring

seminar someone stated that they thought the FAA was going to require radios

with the 8.33 MHz spacing starting in 2020.



Can anyone help me?



Thank you in advance.



Paul Remde

Cumulus Soaring, Inc.

Yes Google would answer all your questions. 8.3 kHz ain't happening in the USA anytime soon. And one issue there is the FAA in their "wisdom" have been playing with Nextcom, a VDL based future digital voice system. (VDL is one of the existing digital link technologies that was also a potential ADS-B carrier, but is effectively not used for ADS-B).

http://www.aviationtoday.com/av/comm...XCOM_1201.html

and see

http://www.roger-wilco.net/8-33-khz-...-what-is-this/

Presumably would be introduced in transport category and other high-flying aircraft. Yes the same folks that thought going dual-link ADS-B was a good idea... your tax dollars at work, sigh. It would not surprise me to eventually see 8.3 kHz spacing in the USA, and that would actually be a good think IMNSHO vs. trying to go digital.

Any mentions of cellular communication standard here are irrelevant, terrestrial type cellular systems don't work well with aircraft in the air and "spamming" multiple cells. For digital links there are technology (like VDL) that are already fairly well understood. FM based systems (like FRS, which is low-power and also irrelevant here) are also non-starters, being FM does not inherently solve bandwidth issues and FM suffers from capture effect/overtalk issues (why we use AM to start with).

Darryl

and FM suffers from capture effect/overtalk issues (why we use AM to start with).

Darryl

Darryl,
Please explain these terms. I always thought aviation used the
outdated AM because that's what they started with many years ago.
After having used 2 meter FM radios for many years I find them to be
vastly superior to aircraft band AM radios.

This would be a great solution then to the team flying dilemma. Simply purchase a modern radio and fly on channels entirely unused on the USA.

Im ordering one today.

Sean
F2

Unfortunately those "unused" 8.3kHz channels don't actually exist - they are already occupied by the existing 25kHz channels. Also any radio you use to transmit here in the USA has to be type approved and current approval doesn't include the 8.3kHz units.

Sorry!

On 4/24/2013 12:43 PM, soartech wrote:
and FM suffers from capture effect/overtalk issues (why we use AM to start with).

Darryl

Darryl,
Please explain these terms. I always thought aviation used the
outdated AM because that's what they started with many years ago.
After having used 2 meter FM radios for many years I find them to be
vastly superior to aircraft band AM radios.

The advantage of AM is that when two people talk at once you hear them
both. With FM, you get the strongest signal or, when both signals are
nearly equal in strength, you hear neither. I'll take AM for aviation
radio. For ham VHF/UHF, it's FM/SSB/digital. :-)

Tony "6N", W1DYS

On Wednesday, April 24, 2013 4:31:35 PM UTC-7, Tony V wrote:
On 4/24/2013 12:43 PM, soartech wrote:

and FM suffers from capture effect/overtalk issues (why we use AM to start with).



Darryl



Darryl,

Please explain these terms. I always thought aviation used the

outdated AM because that's what they started with many years ago.

After having used 2 meter FM radios for many years I find them to be

vastly superior to aircraft band AM radios.



The advantage of AM is that when two people talk at once you hear them

both. With FM, you get the strongest signal or, when both signals are

nearly equal in strength, you hear neither. I'll take AM for aviation

radio. For ham VHF/UHF, it's FM/SSB/digital. :-)



Tony "6N", W1DYS

What he said...

Darryl