[Telecom] Reverse 911

I forget whether you are correct about memory being the second thing.

As for CONELRAD, this semi-duplicates my other submission, stations that were assigned to one of those frequencies for normal operation would be part of the emergency news network. In addition other stations that were _close_ to those frequencies would be utilized (after the minor transmitter re-tuning needed).

Station density was such that any location would be within range of any of several stations on either frequency.

Each station would be on the air for a short period, then power off while each of it's 'neighbors' cycled on.

With semi-random switching between transmitters, and a comparatively short 'on' time for any given transmitter, RDF-based navigation was made very difficult.

The emergency news stations were of comparatively high power (I _think_ 25kw minimum, many were 'legal max' 50kw stations) in conventional operation, so that each had a fairly large service area, even during daylight hours. In a war emergency, they may well have been capable of running at significantly higher levels. High-power stations _are_ an advantage -- transmitters can be further apart (causing larger RDF errors when the active station changes), and each station can operate less often, because more stations can reach any given location.

***** Moderator's Note *****

During a previous life, I was a broadcast engineer, and although your explanation makes military sense, I'm going to contradict _my_ previous remarks and think aloud here.

Consider:

  • Cycling an AM transmitter on and off might seem easy in our modern world, but don't forget that they were working with vacuum tubes and power levels sometimes exceeding 70,000 watts (In the U.S., a station's power rating is the _output_ power, not what goes _in_ to the transmitter: at those power levels, many of the units have to be _water_ cooled). It can take several minutes to turn such a transmitter on, which doesn't make sense if the CONELRAD stations were supposed to switch on and off again and again.

  • Most U.S. AM broadcast antenna arrays are designed to put signal nulls in specific directions, to "protect" other stations that share the same frequency. In other words, most AM stations are "Directional", and have multi-tower arrays. Because of this, the antennas are highly reactive, i.e., they are _very_ sensitive to frequency excursions away from their design center. Retuning such an array, even assuming that the directionality of the antennas wasn't considered, is a time consuming, error prone job that DJ's and station managers just aren't trained for, especially during an emergency: even if the output phasor coils were pre-set to switch via relay, the transmitter would have to be retuned for the new reactance anyway, or it would have to be equiped for multi-frequency operation at the factory.

It sounds like a system designed to fail: too much complexity, too many changes, too much of all the wrong ingredients for an emergency communications network. Also, there's the cost: special-assembly transmitters and phasors, custom antenna engineering, out-of-hours maintenance and a more failure-prone signal during the regular day when managers are trying to meet the payroll.

OK, we need a history lesson: who's out there that can cite the authoritative references?

Bill Horne Temporary Moderator

(Please put [Telecom] in the subject line of your post, or I may never see it. Thanks!)

Reply to
Robert Bonomi
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Yes, because several local AM stations still have them in place. We have one station with a Bauer transmitter where the tuning marks for 640KC are still on the panel, and the crystal oven is still in place to be switched over.

The good news is that not all stations had to go to conelrad channels, but a lot of them did, and the more that did, the more confused folks using AM for navigation would get.

The better news is that stations with directional antenna arrays would go to a nondirectional pattern, which means you had only one stick to load up for 640KC and didn't have to worry about all the fancy phasing networks.

--scott

Reply to
Scott Dorsey

Remember that with nuclear bombers _already_en_route_ to your locale,

*NOBODY* *CARED* about what happened to the effective lifetime of the equipment. :)

In addition, while a 'cold start' power-up does take non-trivial time for big gear, switching from 'stand-by' to transmit, is an entirely different kettle of fish. "Ham" operators routinely do it in fractional seconds, at kilowatt levels, with home-built equipment. Then, look at the LORAN network; sub-second pulse-burse transmissions, at power levels an order of magnitude higher then AM broadcast. As long as the 'final' filaments are warm, you

-can- cycle the "B+" fairly quickly.

Also, you have to take into account the 'threat' involved. *NOT ballistic missiles, but jet bombers -- sub-sonic to slightly supersonic speeds. The time-scale is _hours_. 'Rapid' cycling was not required. IIRC there were (on the close order of) six transmitter changes per hour.

"Yeabut" applies. In emergency mode, the stations dropped the secondary radiators, and transmitted only on the primary tower. And, _that_ antenna, operating alone, is only somewhat more sensitive to frequency excursions than, say, the receiving antenna in a car. One adjustment to the loading coil gets it "good enough for a government job". Remember, again, the 'operating conditions' where this would be used -- *NOBODY*CARES* whether or not it's a 'clean', or 'efficient' signal.

It wasn't -that- bad.

Yeah, the transmitter need another crystal, crystal oven, and a selecting switch. This is a _comparatively_ petty-cash expense item.

Didn't need anything special on the phasors, as they were used only for normal operation. (bypass the phasor array, direct to the primary antenna load, for CONELRAD ops.)

Very little additional 'antenna engineering' required -- the prime radiator used alone (assuming a directional array) was 'broad enough' to serve.

All the stations were of a size/class that a 'FCC 1st class' licensed engineer was required on duty at the transmitter location at all times. And there was 'the book', that detailed the steps for switching over to the emergency frequency. It _wasn't_ push a few buttons; rather it was wrench and screwdriver work. I don't know about these days, but older transmitter facilities used a _lot_ of copper water pipe as the plumbing that carried the signal.

As far as 'designed to fail' goes, consider what was available to work with, circa 1950, and try to design a 'better' system. Requirements: 1) something that _everybody_ can receive, _without_ requiring ongoing and/or continuous adjustment. (Thus, effectively, it needs to be 'set and forget' on the 'public' side. 2) does not provide 'aid and comfort' to the enemy, in the form of reliable navigation beacons. 3) can be accomplished/implemented for a 'reasonable' cost.

Reply to
Robert Bonomi

I think the system was very well designed to accomplish its purpose, but you guys are all missing the point of what that purpose was.

The *REAL* purpose of CONELRAD was to keep the public scared by constantly reminding them of the threat of nuclear war. It was just another "psychological warfare" game the Pentagon played so nobody would ask what they really did for a living.

Just my 2 cents.

Internal Combustion

Reply to
Internal Combustion

I don't know if that was the reason, but the defense systems that was built around many American cities was of little use, Los Angeles for example, by the time they were active we would have been toast.

Reply to
Steven Lichter

All communities within a specified distance of a nuclear power plant have lots of sirens.

Reply to
Sam Spade

I would suggest you do some reading on Joseph Stalin, Kruschev, and the people they had around them. In other words, those people had a long record of brutally murdering millions of their own countrymen, even their own comrades and friends. You think they would've hesitated about killing outsiders? No, they would not.

Having no civilian defense would've resulted in higher casualties than having some sort of plan.

Obviously in the immediate area of ground zero things will be very bad. But there is a very large peripheral area where people in shelters had a better chance of survival.

Aren't people in California trained what to do in caes of earthquake?

Reply to
hancock4

To some extent. During the 1971 Sylmar Earthquake, I was working for GTE and was on duty; really on break at the time in the Sunland CO. We were knocked on our asses and every can cover on the old steppers hit the floor, plus there were so many alarms in the office that the OAF blew it main fuses.

What I mend by defenses were ICBM's that surrounded the Los Angeles area, that made the area a major target because of the military. Years ago I was able to go down one of these holes as they were being removed, we had to take out telecom equipment that belonged to the company.

Reply to
Steven Lichter

wrote

While that is all true, it is also true that the most powerful tool a politician can use to rally support is FEAR. History is replete with examples, culminating in the current administration in Washington.

Reply to
Ken Abrams

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