It’s been a long time since I’ve had some analog fun, so why not a short post of a chance discovery? Unfortunately, it seems I’ve had no time as of late to scan the shortwave bands since I last surveyed the skies for HF RadioFax transmissions. However, the analog nature of radio faxes has been rather intriguing to me, especially when my last successful reception of Russia’s RBW41 station seemed to indicate they were still using mechanical transmission devices.
I’ve learned that such radiofaxes were often adapted from “Wirephoto” transmitters, used to transmit images over a distance by encoding brightness of a scanning spot as an audio signal for transmission usually over telephone lines at the time. This predates the modern (but now antiquated) digital Group 3 fax.
There didn’t seem to be many examples of such Wirephoto transmitters in actual operation, until I stumbled on this short video from @macallister.photos –
Direct Link: https://www.youtube.com/watch?v=JD4H7i0Mu68
You know what? That sounds just like 60LPM radio-fax! But with only 30-seconds, that wouldn’t do … looking around their channel, I found a longer example of a full transmission –
Direct Link: https://www.youtube.com/watch?v=nVCQScaABoQ
This one was sent in the second mode – sounding just like 120LPM radio-fax. It seems the unit has six modes altogether based on the placard on the top – mode 3 and 4 are “AM” while modes 5 and 6 seem to be UPI-specific 120LPM modes in AM and FM respectively.
Because of this, I decided to give it a try decoding it as a radiofax with FLdigi. Turns out, the output is inverted just like RBW41’s output was and the aspect ratio needed some correction, but it seems a ghostly reproduction of the original image is achieved!
The main reason it isn’t any better is likely because of the room acoustics corrupting the signal and the microphone picking up other noises as well. Had it been sent at the slower 60LPM speed or recorded directly from its output, I’m sure the machine would have been able to produce audio that could decode into a more faithful reproduction of the original. The current result makes it rather like a noisy radio-fax. But it is clearly the image that was placed on the drum … even if it is not quite as clear as I would have hoped.
I guess this is a good demonstration of how radiofax and WirePhoto are related! Thanks to @macallister.photos for uploading the clips to show just how this 90-year-old technology works – AP literally wrote an article about it this year! While some people find the noise “annoying,” to me, the sync pulses and patterns are oddly pleasant … “chwee … chwee … chwee …”
Hello!
I’m @macallister.photos
I’m so glad to see your article and appreciate the credit. Many people copied my videos, but they didn’t give me credit.
If you want, I can record the audio directly, reducing the noise. For example, recording from the audio output to an audio line input…
Do you think this is a good idea?
I think we’ll both learn a lot from the experience and this old technology won’t be forgotten.
I look forward to your instructions…
Big hug!
XXXXXXXXXXXXXXXXXX
Hola!
Soy @macallister.photos
Me alegra muchísimo ver tu articulo y agradezco que pusiste mi crédito. Mucha gente copio mis videos, pero no me dieron el crédito.
Si lo deseas puedo realizar una grabación directa del audio reduciendo el ruido. Por ejemplo grabar desde la salida de audio a una entrada de linea de audio…
¿Te parece buena idea?
Creo que ambos aprendemos mucho de la experiencia y no se olvidara esta vieja tecnología.
Espero tus instrucciones…
Gran Abrazo!
Esteban Mac Allister
Dear Esteban Mac Allister (@macallister.photos),
What an honour it is to be contacted by the owner of the videos! I very much appreciate your video demonstrations of the Wirephoto transmitter – it is nice to see such an electromechanical device still operating in good condition. When I heard the sounds of your video, I was immediately reminded about HF radio weatherfax which uses a similar scheme of audio frequency-modulation. Most weather fax stations electronically generate their faxes, but a few years back, receiving Russian transmissions from RBW41 that still seems to be electromechanically scanned possibly from a modified facsimile machine.
For preservation, I would be very interested (if you are willing) if you could get direct audio recordings from the output of the Wirephoto machine, ideally losslessly. As for transmitted material, a test chart involving greyscale bars and/or lines of increasing resolution would probably be very interesting to test the limits (if you have one), or a nice photo which you would be happy to share. It would be most interesting to compare the original material versus the “decoded” version (even though I am decoding it using Fldigi software using modified HF FAX settings, so that isn’t the original equipment you would use to receive a Wirephoto). I am especially interested if you can record the sounds from different transmission modes because the quality and speed tradeoff would be interesting to understand – that would be an excellent and valuable collection. I know this might take quite a bit of time – so I’d appreciate anything you are happy to provide – there is no need to rush :).
Feel free to e-mail me directly if you would like – but I thank you very much for your offer and for taking the time to comment on my post. I hope we can continue to preserve the magic of such important retro-technology.
– Gough
Gough
Creo que podremos divertirnos muchísimo realizando las pruebas del UPI S 16.
Te propongo lo siguiente:
Recuerdo que el UPI solo define 16 niveles de grises.
Voy a imprimir una copia con 16 franjas grises, tratemos de averiguar cuales son los valores adecuados. Seguramente tendremos el gris medio de la fotografía, #767676
Es muy posible que mi UPI S 16 necesite una calibración de laboratorio… No tengo quien pueda realizarla. Al terminar las pruebas, sabremos cuanto lo afecto el tiempo…
Realizo una transmisión y la grabo. ¿Necesito saber qué formato de audio necesitas?, entiendo que comprimir la pista de audio seria un error.
Transmite en 60, 120 y 240 R.P.M
Formato de la imagen: 8×10
Modo AM y FM
Existe una opción internacional con el tambor girando en un sentido y una opción “UPI Domestico” con el tambor girando en el otro sentido (a favor de las agujas del reloj, desde el inicio de la imagen)
Este equipo se encuentra en buenas condiciones porque lo adquirí en fabrican 1990, se trata de una unidad reciclada en fabrica.
Lo use hasta 1994, había apostado a que la digitalización de la fotografía tardaría un poco mas… Pero en 1994 ya dispuse de un Scanner Polaroid SE 35 y una Mac portátil…
Te cuento varias cosas:
En la oficina argentina de Associated Press recibían la transmisión original por radio frecuencia y la grababan en un Revox A 77. Luego cuando necesitaban imprimir una foto, buscaban el registro, lo reproducían e imprimían en la receptora “Unifax II” y te llevabas la copia impresa en papel térmico (Papel de fax…)
Mis inicios como fotógrafo de prensa fueron el la agencia “Noticias Argentinas”, un desprendimiento de la UPI al cerrar en 1974. Cuando comencé a trabajar en 1988, disponíamos de una “linea telefónica dedicada” punto a punto con una oficina de ENCoTel (Empresa Nacional de Comunicaciones y Telecomunicaciones). Ellos transmitían la señal en onda corta y en receptores adecuados, los diarios de diferentes ciudades de Argentina, recibían las imágenes.
Antes de la receptora UNIFAX II, existió una receptora que imprimir un negativo de 4×5 pulgadas. Tenia una caja estanca a la luz, la placa se debía revelar en un cuarto oscuro…
En 1992 existió una placa para insertar en las ranuras de las AT 386, que recibía la señal analógica y la digitalizaba. También había otra placa para ingresar la señal de Telex y convertirla en texto plano.
Entiendo que la normativa de las radio fotos, es la misma que la de muchos satélites antiguos que analizan el clima, una empresa local desarrollo a principios de la década de 1990 una placa para recibir la señal y digitalizarla, para ser utilizadas en el barco rompe hielos argentino y en las bases de la Antártida.
Por favor envíame tu mail por privado, así continuamos la comunicación.
Saludos!
Mac.-