A month ago a new FM Radio station was launched in our city. Since
that time my car radio (2 years old) had been hijacked. Whenever I
pick another station it plays for a split second then the radio scans
to the new station. Can you tell me what it going on and what I can
do about it?

Thanks

Bruce

On Jul 30, 11:34 pm, Trekker wrote:
A month ago a new FM Radio station was launched in our city. Since
that time my car radio (2 years old) had been hijacked. Whenever I
pick another station it plays for a split second then the radio scans
to the new station. Can you tell me what it going on and what I can
do about it?

Perhaps this is what's causing your problem?

http://www.ksat.com/technology/13762279/detail.html

(quoted text)

Drivers don't have to adjust their car's radio dial, because some Des
Moines stations are changing themselves.

A new digital signal is causing a few glitches for some car radios.

The problem started a few weeks ago. Fans of 93.3 FM and 102.5 FM
noticed their radio station presets would sometimes refuse to stay on
the right station.

Drivers would find that when they push their preset button that is set
to 93.3 FM, it stays for a second and then switches back to 102.5 FM
by itself.

GM and Chrysler dealers are trying to repair car radios in Des Moines.

It turns out it's not the radio, it's the signal.

Des Moines Radio Group, which owns the two stations, just began
broadcasting a digital signal.

In some newer cars, that signal will tell drivers what song is playing
and the artist. It's that signal that is confusing some radios.

"There are always quirks and growing pains with new technology, but
this is the strangest I've seen," said Joe Farrington, chief engineer
of the Des Moines Radio Group.

The radio station said it is aware of the problem and will replace
some equipment will have it fixed in a month or so.

On Tue, 31 Jul 2007 15:42:52 +0000, w0jrm wrote:
Drivers don't have to adjust their car's radio dial, because some Des
Moines stations are changing themselves.

A new digital signal is causing a few glitches for some car radios.

The problem started a few weeks ago. Fans of 93.3 FM and 102.5 FM
noticed their radio station presets would sometimes refuse to stay on
the right station.

Drivers would find that when they push their preset button that is set
to 93.3 FM, it stays for a second and then switches back to 102.5 FM
by itself.

I STRONGLY suspect that what's going on in Des Moines is an
improperly-configured RDS encoder. This is not directly related to the
new IBOC digital radio system in use here in the States, but it seems that
the IBOC digital encoders also include an RDS encoder for the station's
analog side.

RDS is a 57KHz subcarrier that transmits low-speed data. Information like
the name of the station, a "program identification" code that's invaluable
for DXers as it often maps directly to the call letters (continuous ID!),
sometimes the name of the song/artist that's on the air right now.

It also includes an "alternate frequency" field. This idea came from
Europe where a single station may have a number of transmitters on
different frequencies. The station places all its frequencies in the "AF"
field on all its transmitters. If the radio senses the signal it's tuned
to isn't coming in well, it tries the other frequencies in the AF list,
looking for a better choice.

Multiple-transmitter stations are MUCH less common in the U.S.. I would
imagine many station personnel don't understand what the Alternate
Frequency (AF) field is all about. My guess is that when KIOA-93.3
configured their equipment, they entered the frequency of different (but
commonly-owned) station KSTZ-102.5 in the AF field -- and didn't enter
their own frequency of 93.3. Presumably some models of radio interpret
this as indicating not that 102.5 is an *alternative* frequency of KIOA,
but the *only* frequency.

I've heard of similar problems in other cities. The IBOC digital
deployment is resulting in RDS installations in a LOT of stations that
haven't used it before, and there seem to be a LOT more RDS-enabled
receivers than there were a few years ago.

On Aug 2, 5:13 am, Doug Smith W9WI wrote:

It also includes an "alternate frequency" field. This idea came from
Europe where a single station may have a number of transmitters on
different frequencies. The station places all its frequencies in the "AF"
field on all its transmitters. If the radio senses the signal it's tuned
to isn't coming in well, it tries the other frequencies in the AF list,
looking for a better choice.

This is very handy when you're driving cross-country. The car
radio can hand off from one transmitter to another, while staying
on the same network. This presupposes national radio networks,
of course. :-)

They also have the ability to switch to a different station for
traffic reports, then switch back to whatever you were listening
to. This is sometimes jarring, but I understand the reasoning.

We have nationwide radio networks in Canada from the CBC,
but don't use RDS. Too many AM transmitters to make it work;
probably other issues too.

We played with DAB for a while on L band, but have quietly
walked away from it. There's just one multiplex still on the
air here in Vancouver.

I've often thought wide band FM ham radio (e.g. 10 GHz)
could benefit from RDS ("VE7LDH 10.2 GHz QTHR QSL via buro").

Laura Halliday VE7LDH "Non sequitur. Your ACKs are
Grid: CN89mg uncoordinated."
ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer

On Thu, 02 Aug 2007 08:37:01 -0700, laura halliday wrote:
We have nationwide radio networks in Canada from the CBC,
but don't use RDS. Too many AM transmitters to make it work;
probably other issues too.

Some CBC stations did run RDS for awhile, but I don't recall any of them
using the AF field. (but I only ever saw RDS on the ones that made it
into Tennessee via sporadic-E) I understand they were somehow used in
conjunction with a data-paging scheme, and when that scheme went bust many
of the encoders were shut off.

There really aren't that many AM transmitters left -- offhand I can think
of St. John's (NL), Windsor, Winnipeg, Regina (Watrous), Edmonton,
Calgary, and Vancouver. The four on the Prairies all have FM relays
within the city centre, so I'd imagine the majority of the audience is
listening on FM even there. Apparently you *can* specify an AM frequency
in the AF field - I've seen it done - though while you can direct a
receiver *from* FM *to* AM you obviously can't do it the other way around.

We played with DAB for a while on L band, but have quietly walked away
from it. There's just one multiplex still on the air here in Vancouver.

Yeah, that's unfortunate. Your system provides more choice, better
quality, and no interference to the existing analog service. I suppose
the lack of economies of scale with the U.S. market doomed it. The CRTC
is now considering allowing our IBOC system. (and the CBC has tested it in
Toronto and Peterborough) They seem VERY leery of authorizing it on AM
though.

I've often thought wide band FM ham radio (e.g. 10 GHz) could benefit
from RDS ("VE7LDH 10.2 GHz QTHR QSL via buro").

Interesting idea.

Reportedly some new iPod transmitters include RDS encoders (?!) (along
with some kind of scheme for reading the song title/artist data out of the
iPod) so apparently encoders are available at consumer-practical prices.
The standard is no secret, so someone adequately skilled would probably
have little trouble building one.

On Aug 2, 9:54 am, Doug Smith W9WI wrote:

There really aren't that many AM transmitters left -- offhand I can think
of St. John's (NL), Windsor, Winnipeg, Regina (Watrous), Edmonton,
Calgary, and Vancouver. The four on the Prairies all have FM relays
within the city centre, so I'd imagine the majority of the audience is
listening on FM even there. Apparently you *can* specify an AM frequency
in the AF field - I've seen it done - though while you can direct a
receiver *from* FM *to* AM you obviously can't do it the other way around.

There are still Radio 1 repeaters on AM in small towns. All the new
stuff is on FM. There was a major stink a few years ago when CBC
Toronto traded in their old AM frequency for the last available FM
frequency in the Toronto/Hamilton/Buffalo area.

We played with DAB for a while on L band, but have quietly walked away
from it. There's just one multiplex still on the air here in Vancouver.

Yeah, that's unfortunate. Your system provides more choice, better
quality, and no interference to the existing analog service. I suppose
the lack of economies of scale with the U.S. market doomed it. The CRTC
is now considering allowing our IBOC system. (and the CBC has tested it in
Toronto and Peterborough) They seem VERY leery of authorizing it on AM
though.

The main push for digital radio here is now Sirius. We were using
totally standard Eureka 147, albeit at a different frequency than
Europe. It works, but suffers from spotty coverage due to lousy
transmitters - if they had continued to build it out, it might work
better. But the one piddly little transmitter left on Mount Seymour
gives surprisingly good coverage. I bought a little DAB radio at
Radio Shack, and it works just fine.

One issue that has been raised as a stumbling block to DAB in
the Americas is that multiplexes require stations to share a
frequency - stations that are otherwise competitors.

The only remaining multiplex here has the three CBC English
networks and the two CBC French networks. The other multi-
plexes, before they were turned down, had stations owned by
the same companies on them (Corus, CHUM).

We (hams) have oodles of bandwidth in our microwave
bands. We could play with this stuff too.

Laura Halliday VE7LDH "Non sequitur. Your ACKS are
Grid: CN89mg uncoordinated."
ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer

Perhaps this is what's causing your problem?


No that's not it at all. I live in Lebanon, Pa and the local radio
station hijacks my shortwave rcvr in FM mode all the time. More watts
means more listeners!