Hello BRATS ATV Enthusiasts:
T-MARC recently distributed a draft for proposed 70cm band plan changes. Since the draft includes passages of particular impact to ATV in that band, the enclosed response was sent from our club to T-MARC.
To: T-MARCDate: Tuesday, July 9, 2019
Subject: Comments regarding the proposed 70cm band plan changes
The Baltimore Radio Amateur Television Society (BRATS) has operated one of the earliest NTSC repeaters since the 1970s. In keeping with that history, we have been developing a dual-mode NTSC and DVB-T software ATV repeater which will allow us to transmit a 6MHz DVB-T signal. The W3WCQ Memorial ATV/DATV Repeater is the first software based dual-mode ATV repeater in the country.
While the BRATS understands a digital TV signal, even one substantially weaker than a comparable analog signal, can impact nearby FM repeaters, we feel by limiting 70 cm amateur television to analog NTSC does a disservice to the Amateur Radio community, our community of Amateur TV operators, and the experimental spirit of Amateur Radio.
The BRATS ATV repeater has historically utilized a reverse allocation in regards to our transmit and receive frequencies. Although this pairing has been in place for over 40 years, we have identified that our omnidirectional transmitter output has the potential of causing interference to FM repeater inputs allocated within 438 – 444MHz in the Baltimore region.
In an effort to eliminate the potential for interference of our ATV transmitter to FM repeater inputs allocated to 438 – 444MHz, the BRATS would like to propose a modification to our allocation to swap our allocated transmit and receive frequencies to align our ATV repeater closer to the ARRL bandplan. (http://www.arrl.org/band-plan)
This modification would prevent any signals from our repeater from interfering with FM repeaters by allocating our ATV output to below 432MHz. As most ATV users have directional antennas and transmit on low power with analog ATV, this would minimize or eliminate any possible interference to FM repeaters.
In the interests of our Amateur Radio and the Amateur TV community, please consider our proposal above to prevent interference from our ATV repeater to FM repeaters and to not forbid the use of Digital ATV on the 70cm band.