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September 2015
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Computer Networking and Telecommunications Research

Walkie Talkies, Car Telephones and Pagers

The mobile phone owes its existence to several technologies that developed the concept of hand-held portable radio communications. In this section we review some of them.


Walkie Talkie

The design of the first products that resemble today’s mobile phone started with Motorola and their pioneering work that led to the launch of the walkie-talkie, epitomised by the SCR536 used by the American Military in World War Two. Indeed Motorola marketed their later models as Handie-Talkies (HT) to reflect the fact that they could be carried in one hand and to distinguish them from larger products that were often contained within a back pack. A walkie-talkie is a hand-held two way radio transceiver in which a push to talk feature allows one radio to transmit and all of the others in range to listen. It was Motorola's experience gained in developing the walkie-talkie that led them to pioneer the creation of the first true mobile phones in the form of their 8000X series.



HT-1E Walkie Talkie

The HT-1E walkie-talkie was manufactured for the Village Radio Program sponsored by the CIA during the Vietnam War. These radios were designed to be simple and robust and were supplied to local people so that they could keep the USA informed about Viet Cong movements. The penalty for being discovered with one of these radios was execution and for that reason, no maker’s or other identifying marks can be found on the radio.

It is powered from 8 D size batteries (12V) and has an external aerial that is 1 foot when retracted and over 6 feet when extended. The case is made from extruded aluminium and the radio has a squelch, volume control and external connectors for aerial, battery and earphone. It operates on a single crystal controlled frequency between 30 to 40 MHz using AM with a power output of 0.5W.


Private Mobile Radio

A further development in mobile communications was the private mobile radio (PMR) network. Developed as part of the Land Mobile Radio Service, within a PMR system, a single radio transmitter was able to communicate with a range of hand-held transceivers however, in small areas direct communication between mobile handsets is possible. One of the biggest users of this technology is the emergency services with the Pye PF1 being the first ever private UHF radio transceiver to be used by the UK Police.

Private Mobile Radio systems are often now termed Professional Business Radio and are allocated to a range of licensed frequencies within the VHF (30 to 300MHz) and UHF (300MHz to 3GHz) bands. In addition, PMR446 offers a licence free set of frequencies within Europe for consumer grade walkie-talkies. A total of eight FM channels, separated by 12.5kHz are assigned from 446.00625MHz and sixteen digital channels at 3.6kbps, separated by 6.25kHz are allocated from 446.103125MHz.

Today the emergency services use the 1995 European Standard, Terrestrial Trunked Radio (TETRA), system for their professional mobile radio communication services.


Burndept BE470 Police Radio

Shown here is the Burndept BE-470 – UHF 3 channel PMR transceiver which was introduced in 1965 but remained in use with both the police and fire service until the 1980s.

In popular culture, this is the radio that featured in the BBC Television police drama “Juliet Bravo” and was also used by DI Alex Drake in the BBC's Ashes to Ashes series.


Car Telephones

Using radio within vehicles was the first stage in the development of today’s cellular mobile phone networks. It was Bell Laboratories who, in 1946, demonstrated in the USA the first radio telephone call from a car. By 1948 the service was delivering 30,000 calls per week. In the UK, a public radio telephone service was introduced by the Post Office for customers in South Lancashire on 28th October 1959. The service was controlled by the Peterloo exchange in Manchester with two base stations, one at Winter Hill and the second in Liverpool. It was launched when the Postmaster General, Reginald Bevins, used his car phone to call Lord Rootes, chairman of the Rootes Group, in his London office. This service was subsequently extended to London in 1965 with the opening of the Post Office Tower and on this occasion, the Postmaster General made a telephone call to the TV presenter, Richard Dimbleby, who was travelling in his chauffer driven Rolls Royce.

Overall, the service was promoted to business users on the basis that a telephone in your car could save you both time and money. However, a three minute call using the radio telephone service cost approximately ten times the cost of a similar call made from a domestic land line. In February 1963 there were only 86 radio telephones registered on the service. The extension of the service to London in 1965 increased its capacity to 350 radio telephones and in 1972 the service was further extended to Birmingham, Coventry, South Yorkshire, Glasgow, Edinburgh, Cardiff, Bristol, Newcastle and Middlesbrough.

Within your car, you had a telephone handset near to the driver with the battery and radio transceiver normally located in the boot. Customers had a five digit phone number. To make a call, you picked up the handset, selected a free channel and pressed the call button. This connected you through to an operator. You then gave the operator your car phone number and the number you wished to dial. The operator would then make this call for you and connect it through to your handset. Communication was simplex requiring you to press the talk button when you wanted to speak. To call a radio telephone user from a standard land line required you to first dial the radio telephone service number. An operator would answer and request the five digit number of the radio telephone customer that you wanted to call. The handset in the car would ring and when answered, the operator would connect the call through.

In the 1970s a nine channel radio telephone service was introduced with equipment being supplied by Stornophone, Pye and Marconi. This was extended in 1977 when a 50 channel system was developed by Stornophone which had the added advantage of automatically finding a free radio channel. In 1983 the service was further enhanced with the launch of a fully automated system that eliminated the need to place calls via an operator. The Public Radio Telephone System Four (PRT4) was the final incarnation of the radio telephone before being superseded by the first generation of analogue mobile phone services.


Lynx Dymar 830 FS Radio telephone

A nine channel Lynx 830FS mobile transceiver (car phone) produced in 1975 by Dymar Electronics.




Pye seven channel radio telephone system

This advert from 1954 is promoting the Pye Telecommunications seven channel VHF radio telephone system. Pye was a UK company that was founded in Cambridge in 1896 by William George Pye. Initially they specialised in the design and manufacture of scientific instruments and military radio systems but in February 1944 a wholly owned subsidiary company was formed called Pye Telecommunications Limited to develop VHF radio equipment for the newly emerging civil communications market.

The advert provides the following information:

This 7-channel radio link system has been designed for economy both in initial cost and maintenance demands. This has been achieved without sacrifice of essential facilities or relaxation of performance standards. Both radio and carrier equipment for the 7-channel terminal is housed in a single 6 foot cabinet as illustrated. This equipment is fully tropicalized and suitable for continuous unattended operation in all parts of the world.

Radio frequency range = 60 to 216 MHz
Transmitter output power = 10 watts (50 watts with amplifier)
Baseband (7 channels) = 0.3 to 23.4 kHz
Maximum deviation = 50 kHz

Radio Pagers

A radio pager network provides a one-way communication system that allows call alerts and short messages to be sent to users. Early systems were short range and typically used in hospitals where there was a need to contact doctors and nurses quickly. However, as the technology developed, so these services were broadened out to provide country wide coverage with services being offered to business users and the general public. The first systems were introduced in North America in 1963 and for the UK, the first wide area radio paging service was introduced by the GPO in 1973 and covered the Thames Valley area. This was extended to London in January 1977 with a service that covered 800 square miles based around a radiopaging centre in Faringdon. By July of that same year the service had attracted a total of 3,000 customers and by 1981 the service had been extended to give virtually nationwide coverage.

With radio paging a user carries with them a small device that is able to receive signals from the radio paging network base stations. Anyone wishing to send an alert to such a user calls the appropriate radio paging service and provides the number of the radio pager that they wish to contact. A message is then sent to that pager and an audible alert sounded. The pager can display a simple numeric message, normally the number of the person calling them, which allows the user to know who is trying to contact them. They could then return the call using a conventional telephone. Later designs of pagers allowed for alphanumeric messages to be displayed on the pager.

Public Wide Area Paging Services in the UK supported three types of pager; one that simply provided an audible beep, often called bleepers, that alerted the user to call a predefined number to receive a message, numeric pagers that could display a sequence of digits and message pagers that could display more complex strings of alphanumeric characters. Within the UK public paging is allocated frequencies in the 105 to 170MHz and 450 to 470 MHz VHF and UHF bands. The transmission of messages, numeric or otherwise, over the paging network required new transmission standards and protocols. In December 1975, the Post Office Code Standardisation Advisory Group (POCSAG) was established that developed a code originally proposed by Philips Research laboratories, into the POCSAG paging code that was released in 1978. The PCSAG protocols operated at data rates of 512 bps, 1200 bps and 2400bps. In February 1996, it was announced that the UK's four radiopaging providers BTCellnet Paging, Mercury Paging Ltd (later becoming PageOne Communications Limited), Vodaphone Paging, and HutchisonPaging were to be allocated internationally agreed frequencies in the 169.4MHz to 169.8MHz spectrum in line with the European Radio Messaging Service (ERMES) however, this did not materialize.

Radio pagers remained popular and successful into the early 1990s until the growth and expansion of the cellular mobile phone. Today radio pagers remain in use but are confined to specialist applications often in the medical and emergency professions.



British Telecom Radiopaging Service

A 1984 leaflet for the British Telecom Radiopaging service carried the strap line, the communication system of tomorrow is available today. It went on to say that radiopaging offered an exclusive opportunity for businesses on the move everywhere. You're never out of touch with British Telecom radiopaging. Five radiopagers were offered. Tone page provided four different tones so that you could differentiate calls say, from home and work. Silent Page added a vibrate option and Safe Page was specifically designed to be compliant with standards relating to hazardous environments such as those with explosive atmospheres. Display Page, which had been launched in 1983, could display a numeric message of up to 20 digits on an in-built screen and Message Master, which was actually launched in 1985, was the first pager that could display a full written message of up to 90 characters in length. The UK was divided up into 40 radiopaging zones with customers needing to pay for those areas in which they wished to receive calls. The Display page service had an initial charge of £10 with a quarterly rental of £51and roaming which allowed the radiopager to operate in more than one zone, was charged at an additional monthly rental of £1.25 per zone. Pagers could be rented starting from £11 per month.


BT EasyReach Uno Pager

As can be seen, this BT EasyReach Uno Pager was manufactured by Philips and was available in the late 1990s. The top display, which was visible when attached to a belt, was backlit and could display 12 numeric digits. When registered with a paging service, you were able to setup a personalised welcome message which callers would here. Thereafter, the pager could store 12 messages, each of which could be up to 20 digits in length. All such messages are timed stamped with the pager not only providing a clock function but also an alarm. It was powered by an AAA battery, had a low battery alarm and could retain data whilst the batteries were removed. In addition to an audible alert, the pager provided a vibrate function.


BT EasyReach Messager 55 Pager

This EasyReach Pager was a Calling Party Pays (CPP) Pager that was available in the late 1990s and was targeted at the young family market. The backlit display which faces upwards when attached to a belt, could display 12 numeric digits. It could store up to 8 messages of up to 20 digits each and had both an audible alert and vibrate option. The in-built clock ensured that all received messages were time and date stamped. It was powered by an AAA battery and had a low battery warning.


Cellnet 600 Plus Pager

This Cellnet 600 Plus Pager offered an audible alert but had no display.

Unfortunately nothing else is known about the function and features of this pager.


Hutchison Telecom PRG1033 Pager

This Hutchison Pager was manufactured by Philips.

Unfortunately nothing else is known about the function and features of this pager.


Philips Bleeper Pager

This Philips Bleeper Pager was used within the UK Home Office. It provided an audible alert only.

Unfortunately nothing else is known about the function and features of this pager.


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