ZEVS Transmitter Explained

The ZEVS transmitter is a type of radio transmitter that uses a vacuum tube to amplify the signal.

It was invented by Vladimir Zworykin in the 1920s, a Russian-born inventor who is often credited with developing the first all-electronic television system.

The ZEVS transmitter is essentially a modified version of Zworykin's earlier TV system, which used a combination of cathode rays and amplifiers to produce a high-quality image.

ZEVS transmitters were widely used in the early days of television broadcasting, particularly in the United States and Europe.

Suggestion: Where to Find Used Iphones

The ZEVS transmitter is a facility of the Russian Navy located near Murmansk on the Kola Peninsula. It's used to transmit messages to submerged submarines in deep water using extremely low frequency (ELF) waves.

ZEVS works on a frequency of 82 hertz, which is quite low, and can only be used for very rudimentary transmissions. This is due to its extreme low frequency.

You might like: Radio Frequency Rf Spectrum Analyzer

The antenna used by ZEVS is a ground dipole, an arrangement of two widely separated electrodes that feed the transmission current into the ground. This is a unique setup compared to standard transmitters.

ZEVS consists of two units, situated at specific coordinates, and is supplied by Kolenergo with electricity. Each unit has a designation, PS-373 and PS-393, and a transmission rating of 7.478 MVA and 7.446 MVA respectively.

The total transmission power of the ZEVS transmitter may be between 10 MW and 14 MW, making it the most powerful transmitter in Europe. This is due to the combined power of the two units.

ZEVS uses MFSK modulation, which involves transmitting messages as 4-minute symbols on specific frequencies around 82 Hz. The symbol time is 4 minutes, and the transmission speed is very low.

A typical message starts with a signal at 82.0 Hz, which lasts at least 4 minutes, followed by 7 symbols transmitted on different frequencies. Then, another 82.0 Hz signal is transmitted for at least one symbol time.

The transmission speed is 0.00416 baud, which is extremely slow, and only short messages are possible. This is due to the low transmission speed of 0.05 bit/s.

You might enjoy: Military Cofdm Wireless Signal Transmitter

ZEVS messages are automatically found and analyzed using software that parses the ZEVS data files.

The software uses a script called parse_zevsdir.py to identify the strongest frequency among the ZEVS frequencies in each data file.

Each message sequence in the data is identified as a repetition of 82.0Hz followed by a message consisting of frequencies other than 82.0Hz, and then 82.0Hz again.

The software generates a file called zevs_messages.txt that contains the UTC time, number of symbols in the message, symbol frequencies, a text representation of the message, and the number of times the message appeared.

Using the software, we can automatically find all the times when a message was transmitted, the message contents, and generate spectrograms of all messages.

A typical message starts with a signal at 82.0Hz that lasts at least 4 minutes, followed by 7 symbols transmitted on frequencies other than 82.0Hz, and then another signal at 82.0Hz.

The transmission speed is very low, with one symbol taking 4 minutes, resulting in a transmission speed of 0.00416 baud and 0.05 bit/s.

Discover more: High-capacity Data Radio

Most messages in ZEVS transmissions are unique, with only a few repeating more than 3 times out of 401 detected messages.

Out of 401 detected messages, 316 are unique, indicating a low repetition rate.

The script find_zevs_transmissions.py looks for a message sequence in the data, which is: 82.0Hz, a message consisting of frequencies other than 82.0Hz, 82.0Hz. This sequence is used to identify repeated messages.

The most common message structure starts with 82.0Hz, followed by 7 symbols with frequencies other than 82.0Hz, and then 82.0Hz again. This type of message is the most frequent.

In some cases, the 82.0Hz carrier between messages is shortened to one symbol time, indicating a possible variation in transmission protocols.

There are instances where messages have a different number of symbols than 7, such as a 2 symbol message, and a 7 symbol message, which may be a valid message or a transmission error.

The carrier wave is a crucial aspect of the ZEVS transmitter. It's transmitted at a frequency of 82.0Hz. This carrier wave is transmitted before and after messages, and sometimes it's transmitted for a while, while other times it's on for much longer periods.

The amount of time the carrier wave is transmitted each day is relatively consistent, with only occasional days where the receiver experiences issues. However, there are periods where ZEVS transmits much less of the 82.0Hz carrier, and these dates don't seem to match any known historical events.

On some days, the carrier wave is transmitted in an interrupted pattern, similar to how amateur radio operators might send test signals using short carriers and breaks. This was observed on 2021-10-26 at 9:00, and it's unclear whether this is a test signal or something else.

A dataset of 9 months of ELF receiver monitoring ZEVS at 80.0-84.0Hz has been published.

The data includes approximately 2 months of breaks and has been made available for analysis.

Software to automatically analyze the data has also been published, offering several features, including:

The software's algorithms are considered naive, leaving room for human analysis and potential discovery of new message types.