Amateur Television (ATV)

Abstract

Amateur Television, ATV, was presented at the June 16 meeting of the Ames Amateur Radio Club. Michael Wright (K6MFW) demonstrated ATV transmission, reception, and use of ATV equipment. Following is what was presented but this site has additional material.

What is ATV?

ATV is not

• Webcam
• Cellphone cam
• Digital Linking Project
• WLAN, WIFI
• Fax
• Internet related
• Broadcast TV
• Wireless Cable TV
• Affiliated with PBS
• Something of non-standard technologies
• Activity available only to the very rich

  SSTV and HDSSTV are subsets of ATV

ATV is amateur (real) television.

Television: The transmission of visual images of moving and stationary objects, generally with accompanying sound, as electromagnetic waves and the reconversion of received waves into visual images.

Transmission mode: NTSC standard: composite video signal with refresh rate of 60 half-frames per second (interlaced). Each frame contains 525 lines and 16 million different colors.

Same mode used by regular TV sets. Hams also call this fastscan TV (FSTV).

* In this context “Amateur” is a legal term meaning compensation free, it does not mean “beginner.” This is why it is against FCC regulations to earn money or conduct business on ham radio frequencies.

So what kind of TV programs?

• Anything you want in the spirit of amateur radio.
• Experiment, show your friends, try new designs, etc.
• In addition to audio, transmit images!

  Don’t do sports and entertainment like commercial TV broadcasting and or charge people for your services. Other restrictions apply such as indecent, libel, scandelous, and other material prohibited by the FCC.

Benefits of ATV

• ATV adds pictures to ham radio transmissions.
• ATV provides opportunities for people to experiment with television.
• ATV provides direct hands-on experience in transmitting television.
• ATV is independent of Internet, networks, centralized systems, and cable TV.
• ATV is independent of media companies, government agencies and budgets.
• ATV can be useful addition to ARES/RACES events.
• ATV is fun.

ARES/RACES Applications

• Hams can provide direct TV coverage from field to an EOC or mobile command post.
• ATV activities can be directly controlled by emergency manager or EC.
• ATV services by hams are zero cost to agency.

• ATV equipment should be readily deployed (my standard is 15 minutes).
• Ham should be competent with ATV equipment.
• ATV activities must never interfere with the event.

• Amateur radio operator must be trained and registered to properly assist when called for assistance.

How to get started in ATV

1. Connect your cable ready TV set to external antenna and tune to local ATV stations.
2. Get an amateur radio license (a no-code technician license also qualifies for ATV)
3. Get an ATV transmitter, companies sell ATV transmitters. All should have a composite video input.
4. Get a video camera. Any camera will work as long as it has composite video output.
5. Get an efficient antenna.
6. Use the best quality lowloss RF cable, cheap cable will not work.
7. Connect the components together.
8. Be adequately dressed and well mannered (don’t scratch yourself in wrong places while on TV).

Using Cable Ready TV Sets

• Many cable TV channels use different frequencies than broadcast.
• Cable channels 57-60 fall within amateur radio frequencies.
• Your TV set is a ham radio receiver!
• Virtually all TV sets and VCRs made in 1990 and later are cable ready.
• Connect your TV set to external antenna and tune in to one of CATV cannels 57-60.
• This is your first step into ATV, see what is there right now!

How Can Regular TV Sets Receive Amateur Frequencies?

Q: Why does cable TV have more channels than what the FCC allocates in the RF spectrum?
A: Cable TV uses frequencies of other radio services in addition to FCC allocations.

This is OK as long as the signal stays contained in the cable!

A sample of frequency allocations for TV channels:
A more comprehensive listing is here.

-------- Broadcast TV --------      --------- Cable TV ----------- 
CH      BAND    VIDEO    AUDIO      CH      BAND    VIDEO    AUDIO
 2    54- 60    55.25    59.75       2    54- 60    55.25    59.75
 3    60- 66    61.25    65.75       3    60- 66    61.25    65.75
 4    66- 72    67.25    71.75       4    66- 72    67.25    71.75

14   470-476   471.25   475.75      14   120-126   121.25   125.75
15   476-482   477.25   481.75      15   126-132   127.25   131.75

57   728-734   729.25   733.75      57   420-426   421.25   425.75
58   734-740   735.25   739.75      58   426-432   427.25   431.75
59   740-746   741.25   745.75      59   432-438   433.25   437.75
60   746-752   747.25   751.75      60   438-444   439.25   443.75

82   cellphones and 2-way radios    82   570-576   571.25   575.75
83   cellphones and 2-way radios    83   576-582   577.25   581.75

84   none                           84   582-588   583.25   587.75
85   none                           85   588-594   589.25   593.75

Other Types of ATV Receivers

• UHF Downconverter not preferred, use cable ready TV set.
• 2.4 GHz receivers (X10 wireless video, lowcost survellienance cams, baby monitors).
      Some of these receive amateur radio frequencies.
• 1.2 GHz receivers (Icom R3 handheld, old analog satellite receivers i.e. Scientific Atlanta 9708).
• PC Electronics, North Country Radio, and other companies carry specialized receivers (Wyman probably no longer available).

ATV Transmitters

• VideoLynx, PC Electronics, North Country Radio, Wyman probably no longer available
• Use ATV transmitters to use frequencies as cable channels 57 through 60
  Coordinate on the UHF band to determine which channel to use.
  Avoid cable channel 61, will interfere with voice and repeaters on 444-450.

RF Cable from ATV Transmitter to Antenna

• Use the highest of quality lowloss coax.
• Cheap cable WILL NOT work.
• Recommended cable is Belden 9913, LMR600, Heliax.
• Low-loss cable is absolutely a must for 1.2GHz and 2.4GHz.

ATV Transmitter Antennas

• Good antenna is paramount.
• Well matched high gain yagi is best.
• Collinear antennas good for omni.
• J-pole good for moderate range omni.

ATV Receiver Antennas

UHF, 440 MHz:

• Does not have to be exotic, but do need good line of sight.
• Yagi is best.
• Most video stations are vertically polarized.
• J-pole and collinear antennas good for omni.
• Can use 75ohm cable TV type coax.
• With good line-of-sight, even rabbit ears can work.
• Avoid consumer type TV antennas, very poor gain, too broadband.

  1.2GHz and 2.4GHz:

• Need good line of sight.
• Yagi, J-pole and collinear antennas.
• Must use high quality lowloss coax.

Frequency Bandplans

440 MHz, 70 cm Band

Consumer Cable Ready TV Sets Video Modulators available (new and used) Commercial made ATV transmitters

1.2 GHz, L-Band

Limited market for receivers Commercial made ATV transmitters Warning! You must verify 1.2GHz transmitters operate only on amateur radio frequencies. Never buy anything else, most likely it operates on aeronautical radionavigation frequencies, If company or dealer cannot say exact frequency, then illegal to operate in United States. Never buy and never operate 1.2GHz video transmitters made overseas and sold on ebay!

2.4 GHz S-Band

Commercial made ATV transmitters and receivers available. License free (Part 15) devices throughout this band. Congested with many radio services. X10 cameras and other Part 15 wireless video systems use frequencies 2.411, 2.434, 2.453, and 2.473 GHz. Microwave ovens operate at 2.450GHz.

Local ATV Stations in SF Bay Area

K6BEN: 421.25 MHz (cable channel 57), Silicon Valley ATV Group

Connect vertically polarized antenna to cable ready TV set, aim antenna towards Mt. Hamilton (or east San Jose foothills).

W6CX: 427.25 MHz (cable channel 58), Mt. Diablo Amateur Radio Club

Connect vertically polarized antenna to cable ready TV set, aim antenna towards Mt. Diablo (Contra Costa County).

W6YX: 2433.75 MHz (X10 channel B), Stanford Amateur Radio Club

Connect 2.4GHz antenna to 2.4GHz receiver (can also use lowcost X-10 wireless video receivers), aim antenna towards Stanford University in Palo Alto.

ATV Diagrams

Simplex (direct) ATV Application

For More Information...

Amateur Television Info, list of websites, clubs, dealers, etc.

NASA TV Retransmissions

With the upcoming STS-114 flight, we have been working on means for the Ames Amateur Radio Club (AARC) to re-transmit NASA TV on the K6BEN amateur television (ATV) video repeater. For more on ATV evaluation, click here.

ATV Demonstration

ATV was demonstrated at last year’s Moffett Airshow in 2004. Below are visitors viewing ATV at the Ames Amateur Radio Club exhibit. The other picture are some videocaptures of actual ATV transmissions from the club exhibit through the K6BEN repeater (VCR recorded reception in another part of the bay area) Click for more photos of the AARC exhibit at the airshow.