[Lowfer] A question about NDBs

[Steve Dove]

Hi Dave,

The short answer is *Canada*!

US NDBs mostly still use straight AM, or USB AM, with 
nominally 1020Hz modulation, whilst Canada uses (usually) 
USB only AM with 400Hz nominal mod frequency.  It is still 
AM, and can still be demodulated without a BFO.

The long dashes after the ID are called 'DAID' or 'Dash 
After ID';  the length is often a form of telemetry as to 
whether the main or standby TX is on, and/or whether battery 
backup is being used, but is mostly there to fill the 'dead 
air' between IDs and make it easier for users to tune in on.

Straight CW is used in other places (France springs to mind) 
but I don't think you're probably hearing those; there are 
hosts of Really Loud Canadians at night though!

          Cheers,

                  Steve


http://www.w3eee.com


Dave Maples wrote:
> All: Time for some very ignorant questions:
> 
> In the long ago, I used to listen to NDBs on an old BC-348 receiver.  All
> the NDBs used ~1000-Hz MCW on an AM carrier.  Recently I have begun tuning
> through LW again, and now I find both the MCW beacons and other beacons that
> ID in straight CW, and then hold a carrier for a bit, then repeat.
> 
> 1. Since both types of NDBs seem to be aeronautical, I'm puzzled as to how
> many ADF installations can deal with the non-MCW beacons.  Do they now
> contain BFOs?
> 
> 2. When did this type of beacon start deploying?
> 
> Thanks,
> Dave WB4FUR
> 
>