The wave band allocated was 140- 150 metres (2000 to 2143 kHz). The Post Office, who were responsible for radio licencing allocated four frequencies within this band for police use throughout Britain. The Metropolitan Police used 145 metres (2069 kHz).
The use of Morse code for transmissions had become standard, and by 1926, 12 specially trained radio operators rode in the vans, and manned the base station at Scotland Yard.
Before 1927, radio frequencies were not officially allocated - it was a case of "first come - first served". In 1927 the International Telegraph Convention in Washington designated the frequency allocations for radio services worldwide, and set aside specific frequencies for police use.
These early experiments used radio telephony (voice) transmissions in the medium frequency band (wavelengths used were 265 and 730 meters or in today's terms, frequencies of 1320 and 411 kHz, in and just below the AM broadcast band).
At these frequencies and with the low power being used, interference from trams, and other electrical devices was so heavy that communication was very difficult. It was found that Morse code gave better and more accurate communications than voice transmissions
The early mobile equipment in the Crossley vans used a cumbersome aerial system of 5 parallel wires mounted on an adjustable wooden frame on the roof. These were nicknamed "bedsteads". They were replaced in 1926 by less obvious aerials.
The Crossleys were used mainly for coordinating special events such as traffic control at race meetings, parades etc. although the "Flying Squad", a special CID patrol unit used two radio equipped vans (actually ex-ambulances).
In 1922, Inspector Bannon of "Special Branch" discussed with the Paris police their experience with radio, which had been used to coordinate police response to demonstrations, using radio telephone equipment mounted in an aircraft.
As a result of these inquiries, an agreement was made with the Marconi company to install experimental radio equipment at Scotland Yard, and in a vehicle. The following year, 1923, three Crossley police vans were modified to take the wireless equipment.
Cyril Trimnell-Ritchard came from Surry Hills, Sydney. His father wanted him to be a Doctor. He wanted to be an actor. Cyril had the distinction of appearing in Britain’s last silent film, Piccadilly, as well as Blackmail.
The wave band allocated was 140- 150 metres (2000 to 2143 kHz). The Post Office, who were responsible for radio licencing allocated four frequencies within this band for police use throughout Britain. The Metropolitan Police used 145 metres (2069 kHz).
caz4777 8 months ago
The use of Morse code for transmissions had become standard, and by 1926, 12 specially trained radio operators rode in the vans, and manned the base station at Scotland Yard.
Before 1927, radio frequencies were not officially allocated - it was a case of "first come - first served". In 1927 the International Telegraph Convention in Washington designated the frequency allocations for radio services worldwide, and set aside specific frequencies for police use.
caz4777 8 months ago
Comment removed
caz4777 8 months ago
These early experiments used radio telephony (voice) transmissions in the medium frequency band (wavelengths used were 265 and 730 meters or in today's terms, frequencies of 1320 and 411 kHz, in and just below the AM broadcast band).
At these frequencies and with the low power being used, interference from trams, and other electrical devices was so heavy that communication was very difficult. It was found that Morse code gave better and more accurate communications than voice transmissions
caz4777 8 months ago
The early mobile equipment in the Crossley vans used a cumbersome aerial system of 5 parallel wires mounted on an adjustable wooden frame on the roof. These were nicknamed "bedsteads". They were replaced in 1926 by less obvious aerials.
The Crossleys were used mainly for coordinating special events such as traffic control at race meetings, parades etc. although the "Flying Squad", a special CID patrol unit used two radio equipped vans (actually ex-ambulances).
caz4777 8 months ago
In 1922, Inspector Bannon of "Special Branch" discussed with the Paris police their experience with radio, which had been used to coordinate police response to demonstrations, using radio telephone equipment mounted in an aircraft.
As a result of these inquiries, an agreement was made with the Marconi company to install experimental radio equipment at Scotland Yard, and in a vehicle. The following year, 1923, three Crossley police vans were modified to take the wireless equipment.
caz4777 8 months ago
Cyril Trimnell-Ritchard came from Surry Hills, Sydney. His father wanted him to be a Doctor. He wanted to be an actor. Cyril had the distinction of appearing in Britain’s last silent film, Piccadilly, as well as Blackmail.
caz4777 8 months ago 4