Radio RSL

[dbdigital]

While surfing the web for (what else) radio broadcasting info, I came across an interesting radio service from Ofcom known as the Radio Restricted Service License.

It's an easy-to-get sub-LPFM /LPAM service for non-profit organizations. For AM the power is limited to 1 watt, for FM it's 50m/w. There are no specs for antennas but the service contour is limited to 13 km or a little over 8 miles. The stations can run commercials. As a rule for FM, these RSL stations are assigned 87.7 Mhz. Ofcom is very interested in the programming these stations offer, the emphasis being on local/regional programming. So when an organization applies for a license they have to indicate what type of programming will be offered. The licenses cost about $350.00 and are good for 5 years.

I know a group calling itself Radio Ready to Grow has recently petitioned the FCC for an increase in AM part-15 levels to 1 watt. But this RSL service really articulates why such a power increase could be justified and would be a good model to crib from.

Read all about it here: http://www.ofcom.org.uk/radio/ifi/rbl/rsls/

db

 

[rkchgo]

Read all about it here: http://www.ofcom.org.uk/radio/ifi/rbl/rsls/

 

[radiomike]

While surfing the web for (what else) radio broadcasting info, I came across an interesting radio service from Ofcom known as the Radio Restricted Service License.

It's an easy-to-get sub-LPFM /LPAM service for non-profit organizations. For AM the power is limited to 1 watt, for FM it's 50m/w. There are no specs for antennas but the service contour is limited to 13 km or a little over 8 miles. The stations can run commercials. As a rule for FM, these RSL stations are assigned 87.7 Mhz. Ofcom is very interested in the programming these stations offer, the emphasis being on local/regional programming. So when an organization applies for a license they have to indicate what type of programming will be offered. The licenses cost about $350.00 and are good for 5 years.

I know a group calling itself Radio Ready to Grow has recently petitioned the FCC for an increase in AM part-15 levels to 1 watt. But this RSL service really articulates why such a power increase could be justified and would be a good model to crib from.

Read all about it here: http://www.ofcom.org.uk/radio/ifi/rbl/rsls/

db

Considering the problems that Sirius and XM have gotten into, I don't think this will happen anytime soon. Any petition for any increase in Part 15, even for event broadcasts, has been shot down. Also, 87.7 is audio for channel 6 tv,and this won't happen, unless channel 6 is abandonned in the US. So far, that is also not going to occur. Due to the radio systems and development in other continents, and the fact it is not as big a business as the US, you can expect no movement on this.

 

[dbdigital]

Considering the problems that Sirius and XM have gotten into, I don't think this will happen anytime soon. Any petition for any increase in Part 15, even for event broadcasts, has been shot down. Also, 87.7 is audio for channel 6 tv,and this won't happen, unless channel 6 is abandonned in the US. So far, that is also not going to occur. Due to the radio systems and development in other continents, and the fact it is not as big a business as the US, you can expect no movement on this.
[/quote]

Possibly not. I found the concept interesting. If you notice on the map Ofcom provides, the only areas in Britain open for this service are in the country, not the cities.

Supposedly, Ofcom will be relaxing its rules regarding unlicensed broadcast on FM (not allowed at any power level) due to the proliferation of iPod transmitters.

db

 

[ironbear]

RSL is a fine idea for the US, but clearly there are no workable FM frequencies at this time. AM is a different matter, and 1710 kHz. is a logical choice for a 1 Watt service. The FCC clearly wants to auction any new spectrum, however.

 

[Transmitter-Man]

The 1w you read about is in fact 1w EMRP (Effective Monopole Radiated Power).

Based on antenna system efficiency measurements most stations end up running a transmitter output power in the region 5-30w give or take.

There is an antenna height restriction of 20 metres or around 66 feet but this is either expensive and or impractical for most so typically 30 or so feet is used with variations in ground system design.

Typical listening range is 3-5 miles.

However, we do currently have a station here located on the outskirts of London that runs an annual 28 day RSL (28 days is the limit to each broadcast but one is allowed up to two per year) who have a very experienced AM engineer.

They have frequency clearance for 531KHz (best end of the band) and I beliueve run a wire antenna with a very moist ground system. Daytime coverage is comfortably covering the south eastern part of the country, circa 150 miles. Nightime they've been received as far as Germany and Scandinavia!

http://www.susyradio.com/

License condition restrict the use of advertising as well as marketing oneself outside the immediate area.

Phil
Transmitter-Man
London

 

[junglecitizen]

Possibly not. I found the concept interesting. If you notice on the map Ofcom provides, the only areas in Britain open for this service are in the country, not the cities.

That's not the case. There have been at least two RSLs in central Manchester since I moved to the city three months ago.

The real downside is they are very expensive compared to the normal advertising revenues from such a service, and it's not possible to cover all of a significant sized city or town with the power generally licenced to urban RSLs (10-15 watts).

Permanent community licences are a much more interesting development - I can hear three at my location in South Manchester, of which this is one: http://www.allfm.org/

It still doesn't compare to the systems for non-commercial radio in place in some other countries in Europe.

 

[rfry]

The 1w you read about is in fact 1w EMRP (Effective Monopole Radiated Power). ...
Typical listening range is 3-5 miles.

Below are the approximate, calculated distances to two groundwave field strength contours for 1 watt radiated from a 1/4-wave vertical monopole, using a very good radial ground system and the other parameters listed -- based on the FCC's MW propagation curves for the frequency and ground conductivity.

This antenna system is better than permitted for RSL stations in the UK, but will give some perception of the coverage capabilities of this system.

Data:
Frequency = 531 kHz
Radiated Power = 1 watt
Radiation at 1 mile = 3.2 mV/m
Conductivity = 8.0 mS/m

Results:
Contour level > Distance to contour
50 mV/m > 0.0632 miles (needed for center city and industrial areas)
2 mV/m > 1.5603 miles (adequate for useful reception in residential areas using a cheap AM receiver)

Coverage to a good auto radio in open country would be possible for greater distances.

R. Fry http://rfry.org
//

 

[Transmitter-Man]

R,

I cannot but agree with your calc's though I believe we just use a single contour here in the UK, 54db/mV I believe.

Regarding reception there are of course other parameters to take into consideration including noise and interference levels, prevalent, especially at night.

While doing some research a while back it was interesting for me to find out that a 4-wire elevated ground system comfortably matched FS readings of a 120 x 1/4 wave buried ground system.

In fact, when I last visited the US I met up with one of the early pioneers of the elevated ground systems and visited one of his engineered stations in SC, WPCI.

Phil
Transmitter Man
London, UK

 

[dbdigital]

A poster named Neil on the Part 15 site raised this question based upon another poster's desire to start a licensed 1 watt AM service in the U.S. such as they have in Britain. I thought it was an interesting point of discussion and worth repeating here.


"Let's start this with a discussion of the potential range for a 1 watt AM service. If the claims of some posters of achieving 1 to 3 miles range with a 100 mW. AM system are accurate then I predict the range will be increased by the square root of 1watt/100 milliwatts. Thus the range would be about 3.16 times the present range or about 3.16 to 9.5 miles. Keep in mind that the baseline here is reported ranges of 1 to 3 miles under receiving conditions which are not known to me.

Use your own numbers here. Take the usable range that you know you can provide to the typical home listener and multiply that by 3.16. Is that range gain sufficient for you to submit to licensing, competetion for frequencies, interference arbitration, equipment restrictions, and other issues that you don't have to deal with under the current rules?

Looking forward to some good comments about this.

Neil"


db