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← URS-3 ← Easy Chair CIA NRP
The URS-4 was intended as the successor to the URS-1
that had been developed back in 1971.
It supports the same 316 MHz UHF band as the URS-1,
but adds support for the 170 MHz VHF-H band, through an exchangable plug-
in unit.
Furthermore, it offers the same user interface as the
URS-3 and allows the
same accessories to be connected and used in the same manner. This applies
in particular to the ability to record a complete survey onto
(audio) tape
and play it back at the office later. It also offers support for the connection
of a pen recorder (data printer).
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A complete URS-4 consists of an URR-4 receiver
with VHF and UHF plug-ins,
a portable URT-4L transmitter for the low frequencies (170 MHz),
a portable URT-4H transmitter for the high band (316 MHz),
suitable VHF and UHF antennas and a wide
range of accessories.
Note that the URS-4 is a narrow band system (30 kHz) whereas the 1500 MHz
URS-3
is a wide band system (25 MHz).
Development of the URS-4 started in 1978, shortly after introduction
of the URS-3. After several tests and improvements, it went into production
in 1980. In 1982, some modifications were made to the front panel of
the URT-L transmitter. The URS-4 was in production until at least 1991.
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In a telecommunications system, the link budget is the sum of all gains
and losses from transmitter, through the medium to the receiver.
➤ Wikipedia
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The diagram below shows the basic setup of the URS-4 system.
At the left are the 2 transmitters of which the URT-4L is used for the
low band (170 MHz) and the URT-4H covers the high band (316 MHz).
The URT-4H is powered by a single 9V block battery, whilst the
URT-4L needs four AA-size batteries for a total of 6V.
When ON, the transmitter produces a constant
beep that should be picked up by the receiver.
An optional external push-button can be connected to a socket,
to allow the transmitter to send a 1350 Hz MARK tone, allowing easy
identification at the listening post (LP).
Each transmitter needs it own (frequency-specific) Sleevex antenna.
At the right is the URR-4 receiver that should be connected to
two and SRN-55 antenna for the UHF band and a separate
open dipole antenna for the VHF band.
The receiver produces a visible output on an
indicator at its front panel.
Furthermore, sockets are available for the connection of a
pen recorder
and an audio tape recorder, for later reference
and processing the head office.
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The illustration below shows some of the factors that attribute to
path loss, starting with the type and position of the bug and its
antenna at the target area.
The transmitter's signal is attenuated by the distance to the receiver,
the material in which the antenna is embedded, the walls of the building,
any furniture, and by anything else that is in the signal path to the
Listening Post (LP).
Other factors may attribute to the gain of the signal,
such as the transmitter's output power, the gain (if any) of its antenna,
the gain of the receiving antenna and any pre-amplifiers.
In order to predict the propagation of the signal with some
degree of reliability, it may be useful to calculate the sum of all gains and
losses and compare it to the link budget of the entire system.
A detailed path loss survey was usually carried out by the CIA
before planting a bug at a given target.
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All parts and accessories of the URS-4 survey system were supplied in two
standard Samsonite executive style briefcases, such as the one shown in the
image on the right.
Documentation and antennas were stowed in the top lid.
All other parts are stowed in the bottom part, that consist of two layers.
The transmitter and the receiver are directly accessible. Adapters and cables
are stored in the bottom section.
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The image on the right shows an original URT-4L transmitter,
without batteries and without enclosure. The one shown here,
is fully operational and transmits on 169 MHz.
The transmitter is powered by a 4.5V battery, consisting of
three 1.5V AA-size cells, fitted in a battery holder that
is connected to the clips at the bottom of the transmitter.
➤ More information
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A similar but smaller transmitter was supplied for support
of the UHF frequencies in the 316 MHz band. THis transmitter
is somewhat smaller than the URT-4L and is powered by a standard
9V block battery.
Unfortunately, we do not have an URT-9H transmitter in our
collection, so we are unable to show a picture of it at this time.
No image available
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The URR-4 shows great resemblance to the URR-3 receiver.
As we do not have an URR-4 in our collection, we are showing
an image of the URR-3 instead.
The front panel of the URR-4 is wider than that of the URR-3
in order to accomodate the VHF and UHF plug-ins, which is accessible
from the front panel.
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The URR-3 receiver was supplied with two plug-in units, one of which
was installed into a bay at the left side of the front panel. One
plug-in was for the VHF band (169 MHz), whilst the other one was
for the UHF band (316 MHz).
The image on the right shows the VHF variant. It has a BNC socket
for connection of the VHF dipole antenna,
and a rotary switch to select the desired frequency:
168, 169 or 170 MHz.
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When performing a site survey, the results of the path loss
measurements can be printed onto paper, using the Goertz
RE-501 MINOGOR pen recorder shown in the image on the right.
The device is battery powered and prints the data, relative
to time, onto a 20 cm wide thermal paper strip for later
processing.
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In addition to printing the measurement data onto paper,
it was also possible to record it onto a magnetic (audio)
tape, using the UHER recorder shown in the image on the right.
UHER tape recorders were very popular during the 1960s and
1970s, as they were among the first affordable portable
tape recorders with professional performance.
➤ More information
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When transmitting, the URT-4L and URT-4H transmitters produce
a 1250 Hz tone. This can be used a the receiving end to tune-in
on the signal. Both transmitters have an SMB socket to which a
wired push-button can be connected.
Whilst pressing the button, the transmitted tone changes to
1350 Hz, so that the transmitter can easily be identified at
the receiving end.
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For the VHF frequencies around 169 MHz, this standard reference
antenna was used. It is an open dipole of which the impedance has
been matched to the 50Ω output of the transmitter.
The dipole is attached to the end of a horizontal boom at the end
of which is the feed point. It is connected to the receiver via a
5 metre long BNC-BNC cable.
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Receiver UHF antenna
SRN-9M
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For the UHF frequencies around 316 MHz, the
SRN-9 was supplied.
It is basically a center-fed half-wave (½λ) open dipole that is
placed before a reflective shield. The total gain of this antenna is estimated
at 8.5dB.
Inside the boom (between the two dipole elements and the reflector) is
a BALUN that provides correct matching to the coaxial transmission line.
➤ More information
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The URS-4 set was supplied with two complete sets of Sleevex antennas
(three models each), so allow testing with two the independent
transmitters (URT-4L and URT-4H) on VHF and UHF, in combination with the
URR-4 receiver.
Each Sleevex antenna has a colour coded ring at its base, that indicates
the environment (medium or diëlectricum) for which it has been designed.
➤ More information
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- Receiver URR-4
- Plug-in unit for 168 - 169 - 170 MHz
- Plug-in unit for 314.5 - 315.5 - 316.5 MHz
- Transmitter URT-4L (168, 169 or 170 MHz)
- Transmitter URT-4H (314.5, 315.5 or 316.5 MHz)
- Dipole antenna for 169 MHz
- SRN-55 antenna for 316 MHz
- Sleevex antenna for 169 MHz
- Sleevex antenna for 315.5 MHz
- Attenuator 80 dB
- Extender board for internal plug-in cards of URR-4
- Battery input voltage extender
- Tape in/out test cable
- BNC-BNC coax cable 5 m
- DIN-DIN audio cable 1 m
- BNC-Banana cable (1 m) for pen recorder
- Remote button (marker) for URT-4L and URT-4H
- Carrying strap for URR-4
- Spare DIN plug
- 5 spare fuses 100 mA
- Allan wrench
- Screwdriver
- Operation and test manual
- Set of final acceptance test data sheets
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VHF measuring range 70 dB to min. 160 dB ± 3 dB
UHF measuring range 50 dB to min. 140 dB ± 3 dB
Marking range VHF: min. 160 dB, UHF: min. 140 dB
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VHF frequencies 168, 169 and 170 MHz ± 2 kHz
UHF frequencies 314.5, 315.5, and 316.5 MHz ± 3 kHz
Gain accuracy ≤ 0.5 dB
Image suppression VHF ≥ 45 dB, UHF ≥ 40 dB
IF suppression ≥ 70 dB
Input impedance 50 Ω
Noise figure < 4 dB
RF - IF bandwidth 12 kHz ± 2 kHz
Modulation (tone) 1250 Hz ± 10 Hz
Mark tone 1350 Hz ± 10 Hz
Midscale (meter) -99 dB ± 1.5 dB
Indicator accuracy 20-100% of full scale: ± 2dB, 10% of full scale: ± 4dB
Pen recorder out > +500 mV (FSD)
Tape recorder out > 350 mV RMS
Tape input < 350 mV RMS
Frequency out ZERO: 500 Hz ± 15 Hz, FSD: 3000 Hz ± 25 Hz
Voltage +14 to +20 V, minimum: +13.5 V
Current REC: < 30 mA, REPLAY: < 12 mA
Battery 4 x 9V block battery
Dimensions 290 x 200 x 89 mm
Weight (incl. batt.) ?
Temperatureq -18°C to +50°C
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Frequency 168 or 169 or 170 MHz ± 2 kHz
Output power +22 dBm (160 mW) ± 1 dB
Impedance 50 Ω
Harmonic suppression > 30 dB
Tone frequency 1250 Hz ± 10 Hz
Mark frequency 1350 Hz ± 10 Hz
Modulation on-off keying
RF bandsiwdth ≤ 30 kHz
Supply voltage 4.5 to 7 V (minimum 4.5 V)
Current < 320 mA
Battery 4 x AA-size penlight (1.5V each)
Dimensions 61 x 21.5 x 171 mm
Weight ~ 320 grams (without batteries)
Temperature -18°C to +50°C
Antenna type Sleevex
Antenna socket BNC
Mark socket Sub-Minax/F (SMB)
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Frequency 314.5 or 315.5 or 316.5 MHz ± 3 kHz
Output power +2 dBm (1.6 mW) ± 1 dB
Impedance 50 Ω
Harmonic suppression > 30 dB
Tone frequency 1250 Hz ± 10 Hz
Mark frequency 1350 Hz ± 10 Hz
Modulation on-off keying
RF bandsiwdth ≤ 30 kHz
Supply voltage 6.5 to 10 V (minimum 6.5 V)
Current < 10 mA
Battery 9 V block battery
Dimensions 28 x 20 x 165 mm
Weight ~ 150 grams (without batteries)
Temperature -18°C to +50°C
Antenna type Sleevex
Antenna socket BNC/F
Mark socket Sub-Minax/F (SMB)
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- Tentative Proposal for Prototype XURS-4 Equipment
NRP, 8 March 1978. CM302554/A.
- Proposal for Prototype XURS-4 Equipment
NRP, June 1978. CM302554/B.
- Technical Attachment to Proposal for Prototype XURS-4 Equipment
NRP, 8 June 1978. CM302554/C.
- Operating Manual for URS-4 Path Loss Measuring System
NRP, June 1980. CM302554/D.
- Environmental Test Report on XURR-4 Receiver
NRP, August 1980. CM302554/E.
- Environmental Test Report on XURT-4L and XURT-4H Transmitters
NRP, August 1980. CM302554/F.
- Engeneering Considerations Related to XURS-4 Protype Equipment
NRP, September 1980. CM302554/G.
- URT-4L Component Layout (technical drawing)
NRP, November 1982. CM302554/H.
- Operating Manual for URS-4 Path Loss Measuring System
NRP, January 1983. CM302554/I.
- Collection of correspondence between NRP and CIA about URR-4
NRP/CIA, 21 January 1983. CM302554/J.
- Environmental Test Report on URS-4 Path Loss Measuring System
March 1983. CM302554/K.
- Environmental Test Report on URS-4 Path Loss Measuring System
May 1991. CM302554/L.
- XY-YT Miniaturschreiber Minigor, Type RE 501, Bedienungsanleitung
Goetz, Metrawatt AG, Nürnberg (Germany). Date unknown. CM302559/A.
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- NRP/CIA, Collection of documents related to URS-4
Crypto Museum Archive, CM302554 (see above).
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© Crypto Museum. Created: Thursday 10 August 2017. Last changed: Friday, 05 January 2018 - 22:43 CET.
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