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Video transmitters??


RPSharman

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I hate being tethered to the ever-moving DIT or video village. The show I'm on graciously rents down-converters and Canatrans transmitters for me (with some convincing and a good deal from the camera house). Some day I'll not get so lucky, but still won't want to run cable.

I was wondering if there's a lower cost transmitter (ATV or DTV) that people have had success with. It needs to be self-contained, like Modulus/Canatrans. The 2.4/5.8 stuff is pretty useless getting through sets and stages.

Or are Modulus and Canatrans on the way out and cheaply available?

Robert

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Robert, you may want to take a look around this site.

The link is to the 'Steadicam Transmitter' section, they operate on UHF frequencies, are designed to be battery powered and accept an SD signal (so you'll still need a down converter...). There are many other options, at varying levels of DIY-ness.

http://www.rf-video.com/products/senders.asp

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The 2.4/5.8 stuff is pretty useless getting through sets and stages.

Robert

I am in the same boat at the moment and looked into the 5.8GHz video TX/RX offered on Hobbyking. Not sure about the US but 200mW is not legal to use in Germany (25mW). The 1500-2000 meter distance is pretty amazing though. Do a search on youtube and you will see all these FPV users that were flying there little copters around. It does look quite useful for on set. Maybe even 25mW would be enough to cover a normal film-set.

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I am in the same boat at the moment and looked into the 5.8GHz video TX/RX offered on Hobbyking. Not sure about the US but 200mW is not legal to use in Germany (25mW). The 1500-2000 meter distance is pretty amazing though. Do a search on youtube and you will see all these FPV users that were flying there little copters around. It does look quite useful for on set. Maybe even 25mW would be enough to cover a normal film-set.

The helicopters are generally in a field with line of sight. That being said, 2,000 meters is amazing!

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At 5.8ghz antennas can make or break the system. One antenna I have found to be an asset is the skew planar. Works well in 360 degrees, combine it with a circular polarized antenna through a diversity controller and you have a very small system that works well in a video village set up.

David Rogers

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There is a legal way to use UHF TV channels for this purpose. A license IS REQUIRED.

Part 74.870 Wireless video assist devices

Wireless assist video device. An auxiliary station authorized and operated by motion picture and television program producers pursuant to the provisions of this subpart. These stations are intended to transmit over distances of approximately 300 meters for use as an aid in composing camera shots on motion picture and television sets.

Exact quote from FCC Rules:

Television broadcast auxiliary licensees and motion picture and television producers, as defined in §74.801 may operate wireless video assist devices on a non-interference basis on VHF and UHF television channels to assist with production activities.

(a) The use of wireless video assist devices must comply with all provisions of this subpart, except as indicated in paragraphs (B) through (i) of this section.

(B) Wireless video assist devices may only be used for scheduled productions. They may not be used to produce live events and may not be used for electronic news gathering purposes.

© Wireless video assist devices may operate with a bandwidth not to exceed 6 MHz on frequencies in the bands 180–210 MHz (TV channels 8–12) and 470–698 MHz (TV channels 14–51) subject to the following restrictions:

(1) The bandwidth may only occupy a single TV channel.

(2) Operation is prohibited within the 608–614 MHz (TV channel 37) band.

(3) Operation is prohibited within 129 km of a television broadcasting station, including Class A television stations, low power television stations and translator stations.

(4) For the area and frequency combinations listed in the table below, operation is prohibited within the distances indicated from the listed geographic coordinates. (chart of T-Band cities)

(d) Wireless video assist devices are limited to a maximum of 250 milliwatts ERP and must limit power to that necessary to reliably receive a signal at a distance of 300 meters. Wireless video assist devices must comply with the emission limitations of §74.637.

(e) The antenna of a wireless video assist device must be attached to the transmitter either permanently, or by means of a unique connector designed to allow replacement of authorized antennas but prevent the use of unauthorized antennas. When transmitting, the antenna must not be more that 10 meters above ground level.

(f)(1) A license for a wireless video assist device will authorize the license holder to use all frequencies available for wireless video assist devices, subject to the limitations specified in this section.

(2) Licensees may operate as many wireless video assist devices as necessary, subject to the notification procedures of this section.

(g) Notification procedure. Prior to the commencement of transmitting, licensees must notify the local broadcasting coordinator of their intent to transmit. If there is no local coordinator in the intended area of operation, licensees must notify all adjacent channel TV stations within 161 km (100 mi) of the proposed operating area.

(1) Notification must be made at least 10 working days prior to the date of intended transmission.

(2) Notifications must include:

(i) Frequency or frequencies.

(ii) Location.

(iii) Antenna height.

(iv) Emission type(s).

(v) Effective radiated power.

(vi) Intended dates of operation.

(vii) Licensee contact information.

(3)(i) Failure of a local coordinator to respond to a notification request prior to the intended dates of operation indicated on the request will be considered as having the approval of the coordinator. In this case, licensees must in addition notify all co-channel and adjacent channel TV stations within 161 km (100 mi) of the proposed operating area. This notification is for information purposes only and will not enable TV stations to prevent a WAVD from operating, but is intended to help identify the source of interference if any is experienced after a WAVD begins operation.

(ii) If there is no local coordinator in the intended area of operation, failure of any adjacent channel TV station to respond to a notification request prior to the intended dates of operation indicated on the request will be considered as having the approval of the TV station.

(4) Licensees must operate in a manner consistent with the response of the local coordinator, or, if there is no local coordinator in the intended area of operation, the responses of the adjacent channel TV stations. Disagreements may be appealed to the Commission. However, in those instances, the licensee will bear the burden of proof and proceeding to overturn the recommendation of the local coordinator or the co-channel or adjacent channel TV station.

(h) Licenses for wireless video assist devices may not be transferred or assigned.

(i) The product literature that manufacturers include with a wireless assist video device must contain information regarding the requirement for users to obtain an FCC license, the requirement that stations must locate at least 129 kilometers away from a co-channel TV station, the limited class of users that may operate these devices, the authorized uses, the need for users to obtain a license, and the requirement that a local coordinator (or adjacent channel TV stations, if there is no local coordinator) must be notified prior to operation.

Bill Ruck

San Francisco

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The Ricsonix looks good, thanks!

Here it's being more and more rare to have a downconverter available for us on set from video dept. since they are working with digital monitors only.

I've been using a DIY 2.4GHz tx + a receiver for many years. CCTV stuff really. 4 channel but only 10mW, with directional antenna on the rx.

2.4GHz is very sensitive to even someone walking between tx and rx, and even non-smart phones will interfere severely. And using high power to compensate (say 1W) is not very healthy, but the Ricsonix is 100mW which may be fine...

My plan was using a DIY UHF 150mW tx (*) and a small UHF TV/monitor (to have the rx built in) but those TVs are harder to find now, so rethinking the video send, includding the monitor...

I'd love to use low freq, below US block 20, with just 50 mW it would be plenty, but can't find suitable tx and rx.

And still would like advice in currently available small SDI compatible monitors with low power consumption...

(*) Transvideo tx is known for producing strong interferences through audio cable, microphones and wireless mics, so it was never an option for me

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