|
|
|
|
|
|
|
TSCM TEMPEST
RF leak detector
- under construction
4F-130 was a portable RF Leak Detector/Attenuation Meter Kit, introduced around
1991 by Euroshield Oy (now: ETS-Lindgren) in Eura (Finland).
It is intended for testing the performance of EMC shielding enclosures,
such as the RF-shielded rooms inside embassies that are used for
confidential conversations.
The 4F-130 can be used as a countermeasures device (TSCM)
as well as TEMPEST certification tool.
A modern digital version of the 4F-130 is known as the MF-9F [2].
|
The set consists of a separate transmitter and receiver,
each of which is battery powered and has its own collapsible
magenetic loop (H-field) antenna.
The transmitter operates at one of four fixed frequencies:
10 kHz, 156 kHz, 1 MHz and 10 MHz. The receiver has a built-in 8-bit
microprocessor that uses FFT to compare its 40-200 Hz
Intermediate Frequency (IF) spectrum
with the sprectrum that was stored during calibration.
The relative magnitude between the measured magnetic field strength and the
calibrated value, is then shown in dB on the analogue instrument.
|
|
|
|
Supplied with the set are two 30 cm measuring rods that can be fitted to
the top of each loop antenna. They are used to ensure a fixed distance
to the wall of the RF shielded enclosure under test. The manual [A]
describes calibration and measurement procedures according to
MIL-STD-285 1 and NSA 65-6 standards, differing only in the positioning
of the two antennas (coaxial or coplanar). Note that this test set can only
be used for measuring leakage of frequencies up to 10 MHz. For higher
frequencies (e.g. 400 MHz or higher), different test equipment is required.
|
-
Originally known as government specification MIL-S-4957A and used
in the early 1950s for measuring screen mesh enclosures [A].
|
The image below shows the complete system. At the right is the transmitter
which should be placed outside the RF-shielded enclosure under test. It has
an ON/OFF switch and a 4-position rotary switch for selection of the desired
frequency. It is shown here with the antenna in operational position.
At the top of the antenna is a plastic fitting for the measuring rod.
At the left is the receiver, which is housed in a similar enclosure.
It has an ON/OFF switch, a MODE push-button and two LED indicators,
plus an analogue meter which shows the path attenuation in dB.
The receiver should be placed inside the RF-shielded room under test.
|
The diagram below shows the positioning of receiver and transmitter
for each of the measuring standards. The transmitter is always
placed outside the enclosure, whilst the receiver is inside. With the
military standard MIL-STD-285, the transmitter and receiver are placed
in a horizontal plane with the antennas facing each other. This is known
as coplanar or in-line orientation.
With the NSA 65-6 standard, transmitter and receiver are placed
vertically with the antennas in parallel on a common axle, as shown in
the lower part of the diagram. This is known as coaxial or
parallel orientation. It is believed that the NSA method provides
more coupling between the transmission and reception antennas, and
therefore offers a better indication of leakage.
For both standards, the transmission and reception antennas should be
held 30 cm from the RF-shielded wall. The removable measurement rods
can be used to measure this distance accurately. Any contact between
the measuring rod and the metal shielding of the wall should be avoided.
Calibration is done in free space, with a gap between the tips of the
measuring rods that is equal to the thickness of the RF shielded
enclosure under test – as shown in the diagram above – and clicking
the MODE button on the receiver. The devices can be placed
on tripods for more stability.
|
When unused, the transmitter and receiver can be stowed
in the supplied transit case shown in the image on the right, along
with the measuring rods, an instruction booklet and a screwdriver.
The case measures 465 x 390 x 187 mm and weights 8 kg with equipment,
without batteries.
Note that the transmitter and receiver should be stowed back-to-back,
in order to avoid damage to the instrument (meter) and the controls.
|
|
|
The transmitter measures 275 x 150 x 48 mm and weights 1.7 kg.
It is powered by 6 1.5V D-size battery cells that last approx.
10 hours. The transmitter operates at one of four frequencies,
as set by the rotary selector at the front panel.
The transmitter should be placed outside the RF enclosure under test.
At the top of the antenna is a socket for the 30 cm measuring rod,
that can be fitted in one of two positions, depending on the measuring
method (MIL-STD or NSA).
|
|
|
The receiver is housed in a similar enclosure as the transmitter,
and weights 1.8 kg. It should be placed inside the RF enclosure
under test. It has an ON/OFF switch, a calibration button (MODE)
and a large analogue instrument (meter).
Like with the transmitter, a measuring rod can be fitted to the
top of the antenna to ensure a distance of 30 cm to the wall of the
enclosure under test.
During the measurement, the meter shows any leakage in dB.
|
|
|
Two metal measuring rods
of 30 cm each are supplied with the
set. They should be fitted to the top
of the two antennas, to ensure an exact distance
of 30 cm between the antenna and the wall of the enclosure
under test, in accordance with the MIL-STD and NSA standards.
Note that the measuring rods can be fitted in two orientations
(up or forward),
allowing a different orientation for each of the standards.
|
|
|
Each 4F-130 test set came with an instruction booklet that was
stowed inside the transit case. Unfortunately it is missing
from the set featured here, but luckily we were able to extract it
from a 1992 evaluation report of the US Air Force [C].
➤ Download operating instructions
|
|
|
Below is the block diagram of the receiver, as it is presented
in the user manual [A]. At the top left
is the antenna which consists of three loops with two windings
each, all housed in the same metal pipe (for electrical shielding).
The antenna loops can be connected in series by means of a selector –
depending on the selected operating frequency – under control of
a the main CPU.
After buffering and (optional) amplification, the signal is mixed with
one of four fixed frequencies – all derived from the same 10 MHz crystal –
resulting in an intermediate frequency spectrum of 40 to 150 kHz.
After filtering and further amplification this signal is then sampled by
an 8-bit ADC and fed to the CPU which performs a Fast Fourier Transform
(FFT) on it. The results are compared with the calibration values stored
in the internal memory and converted to an analogue value using an 8-bit
DAC, before being fed to the analogue meter at the bottom right.
The main CPU – an Hitachi HD6303RP – runs at 1.25 MHz, which is derived
from the 5 MHz clock signal (10 MHz / 2). It is internally divided
(in the HD6303) by 4.
|
The transmitter is housed in a two-piece enclosure that consists of
two grey extruded aluminium shells, held together by brackets and a locking
spring. To access the interior, the front and rear panels must be removed,
along with the locking brackets and the spring. Note that the front panel
also acts as the access to the battery compartment. Also note that the
nut of the frequency selector
must be removed before separating the case shells, to
avoid damage to the selector.
The image above shows the interior of the transmitter after the upper
case shell has been removed. It consists of an oscillator with four
qauartz crystals, one of which is selected by means of the 4-position
rotary switch at the centre. The signal is then boosted in a Power Amplifier
(PA) before it is fed to the loop antenna. The latter is shown here in
collapsed (storage) position.
|
The receiver his housed in a same-size 2-piece aluminium enclosure, of which
each half contains part of the electronics. The interior can be accessed
by removing the front and rear panels, along with the locking brackets and
the spring. The image below shows the opened unit with the two halves
facing each other tête-à-tête, and the loop antenna in operational (unfolded)
position.
Note that the two halves are interconnected by means of two fragile
14-pin flatcable connectors. Remove the connectors from their sockets
before separating the case shells and be careful not to bend the pins.
When re-assembling the unit, these connectors have to be reseated
carefully.
At the right is the central processing unit
(CPU),
which is normally covered by a metal shield.
It consists of an Hitachi HD6303RP 8-bit microprocessor running at 1.25 MHz, 2KB
CMOS RAM and an 8KB EPROM that holds the firmware. Also present on this
board are an ADC0833 8-bit ADC – for digitising the IF spectrum
– and a DAC0808 8-bit DAC – for driving the analogue meter.
|
|
When we received the set, the transit case and both units (transmitter
and receiver) were in good condition. Testing the transmitter revealed
an intermittend problem however, that was clearly caused by the 4-position
frequency selector at the front panel. Some frequencies did not work.
|
After opening the transmitter for investigation, the cause of the
problem immediately became apparent. The contacts of the 4-position rotary
selector are soldered to the PCB, whilst its shaft is bolted to the
front panel. If the front panel is removed without removing the nut below
the knob first, the selector will be torn to pieces.
Judging from the solder remains at the bottom of the PCB, this was not the
first time, as the selector had clearly been replaced at least once
before. In order to mount an attempt to repair the selector, it
had to be removed from the PCB.
|
|
|
|
Normally, this would not have been a problem, but the questionable
quality of the PCB, the lack of a soldering mask and the fact that
the pins are soldered at both sides of the PCB, made it a real
challenge. As the selector is obscured by several other high components,
several parts had to be removed from the PCB to gain access to the
upper side of the pins of the rotary selector.
|
After desoldering the legs – taking care not to damage
the tracks and the through-plates holes – the selector came out,
but immediately fell apart as shown in the image above.
As it was beyond repair, it had to be replaced.
Luckily, rotary switches of this type (MRC-204) are still available
from several suppliers in the US.
Both sides of the PCB were thoroughly cleaned and a replacement
selector was ordered. When it arrived a week later, its shaft was
shortened to the required length. It was carefully
positioned (not too high, not too low) and soldered in place.
|
|
|
|
Next, the unit was reassembled and tested by applying a 9V DC
voltage directly to the battery terminals and switching the unit on.
It immediately came to life and transmits an AM tone-modulated
signal on any of the (four) selected frequencies.
It is now fully operational again.
|
No manual Broken frequency selector on transmitter
|
- Part of the original manual extracted from a US Government evaluation [C]
- 4-position rotary selector replaced (transmitter)
|
- Original manual
- Original screwdriver
|
Euroshield Oy was a manufacturer of high quality radio frequency (RF) shielding
products used in the electromagnetic compatibility (EMC) industry, located in
Eura (Finland).
On 31 December 1997, Euroshield was taken over by ESCO Electronics Corporation
in Texas (USA) for US$ 3.5 million, and merged into EMC Test Systems (ETS) [3].
In 2000, after the acquisition of Lindgren RF Enclosures, the name of the
company was changed to ETS-Lindgren [1].
|
Device RF leak detector Purpose Testing EMC shielding (TEMPEST) Model 4F-130 Year 1991 Manufacturer Euroshield Frequencies 4 (see below) IF 165 Hz Attenuation 0 - 130 dB Accuracy ± 1.5 dB Display Analogue Indicator Battery check Antenna Electrically shielded 300 mm loop (magnetic loop) Batteries 6 x 1.5V (each) Life 10 hours Temperature 0°C - +40°C 1 (Storage: -5°C - +45°C) Dimensions 275 x 150 x 48 mm (each) Weight RX: 1.8 kg, TX: 1.7 kg Accessories (see below)
|
-
During calibration and measurement, the temperature must not vary
more than 3°C.
|
- 10.165 kHz
- 156.085 kHz
- 1.000165 MHz
- 9.999835 MHz
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Thursday 26 August 2021. Last changed: Monday, 01 April 2024 - 08:56 CET.
|
 |
|
|
|
