The SPAUN SMF 790 filter effectively blocks interference from LTE mobile networks in the 822-1000 MHz band from affecting DVB-T/T2 reception in the 5-790 MHz band. It has a very sharp roll off starting at 792 MHz, reaching -10dB attenuation by 799 MHz and -30dB by 807 MHz, with over -50dB attenuation achieved by 815 MHz. Testing showed the filter performs even better than its specifications, safely blocking LTE signals from impacting digital TV reception.

1. TEST REPORT LTE Filter
SPAUN SMF
790 LTE Stop
Band Filter
• safely blocks interference from LTE
networks
• very easy to install
■The SPAUN SMF 790 filter
inserted next to the antenna • performance better than its
input of a DVB-T receiver. The
filter effectively blocks any specifications
unwanted signals from nearby
LTE mobile phone and data
transmitter • small product but very effective
72 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 04-05/2012 — www.TELE-satellite.com www.TELE-satellite.com — 04-05/2012 — TELE-satellite International — The World‘s Largest Digital TV Trade Magazine 73

2. TEST REPORT LTE Filter
04-05/2012
SPAUN SMF 790 LTE Filter
Do Not Allow LTE Data
Most effective way to block interfe
rence
from LTE (3G) mobile networks
www.TELE -satellite.com/
TELE- satell ite-1205/eng/spaun-s
mf.pdf
Transmissions To Interfere
With Your DVB-T/T2 Reception
3GPP LTE wireless high desired signals. You can eas- component is an amplifier, ment is well shielded and
speed data transmissions ily detect this with an analog a multiswitch, a receiver or the connectors are firmly at-
for mobile phones and data signal (unwanted additional any equipment that requires tached to coaxial cable ends.
terminals may in some cir- white/black dots and audio electric power to operate. If the antenna has a built-
cumstances interfere with noise). With a digital re- In simple installations with in amplifier, you will have no
regular terrestrial TV re- ceiver you can detect it by no additional components, choice but to connect the
ception. That’s because the measuring signal quality. you connect the filter any- filter at the antenna output.
highest part of the classical If signal quality measured where between the antenna The results could be slightly
terrestrial TV range is to- by your receiver changes and the receiver. Probably it worse because LTE signals
day dedicated for LTE rather over time, or worse your will be more practical to put will have the opportunity to
than DVB-T/T2. As digital TV receiver from time to time it next to the receiver. In mix up with terrestrial TV
requires much less band- looses completely the ability more complex installation, signals in the antenna am-
width than analog TV to to process video and audio, the filter should be inserted plifier and can intermodulate
transmit the same number one of possible causes can before the amplifier or the one another. However, such
of TV channels, it became be interference created by multiswitch whatever hap- not desired intermodulation
possible to dedicate part of LTE signals intermodulating pens first when looking from should be minimal in well
its original frequency range with your receiver’s input. It the antenna side. One filter designed amplifiers hav-
for high speed data trans- is very easy to confirm such should be enough for the ing high dynamic range. So
missions. But because most hypothesis: just connect the whole network if only your even if you have an active
of the existing antenna in- SMA 790 and observe if sig- signal distribution equip- antenna with a built-in am-
stallation pass the whole nal quality improves.
frequency range up to 862 For the best results, the
MHz, LTE signals may find SPAUN SMF 790 filter should
their way into your DVB-T/ be placed before the first
T2 receiver’s input. active component of the re-
Despite the fact that LTE ception system. An active
data is transmitted in a dif-
ferent frequency range than
DVB-T/T2 terrestrial signals,
if they are strong enough
they can interfere with reg-
ular TV reception. If LTE
signals are strong and you
do not use any filter, some
intermodulation might take
place in your receiver’s de-
modulator. Spurious signals
created due to intermodu-
lation will manifest them-
selves as excessive noise
degrading the quality of the
74 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 04-05/2012 — www.TELE-satellite.com

3. 1 2 3
4 5 6
1. The SPAUN SMF 790 has a very sharp roll off at the higher end of
the terrestrial/cable frequency range.
2. Up to 792 MHz there is practically no attenuation.
3. At approx. 799 MHz the filter has a 10 dB attenuation.
4. Attenuation increases to 30 dB at approximately 807 MHz.
5. Full 50 dB attenuation is reached at 815 MHz.
6. In accordance with specifications, there is more than 50 dB
attenuation at 822 MHz and above
plifier, it will still make sense analyzer it produces nice
to connect the SMA filter be- spectral views that reveal
fore the next active compo- the true frequency charac-
nent (amplifier, multiswitch, teristics of a filter.
receiver). As our measurements re-
According to its specifi- vealed (and you can see
cations, it should pass the that on the attached screen
range from 5 through 790 shots), the SMF 790 starts
MHz with minimum attenua- rolling off at about 792 MHz
TECHNICAL
DATA
tion while severely attenuate and reaches its maximum Manufacturer SPAUN electronic GmbH & Co. KG, Germany
the frequency band from 822 attenuation at 815 MHz. So Web www.spaun.com
through 1000 MHz (where it is even sharper than the E-mail contact@spaun.com
LTE signals are transmitted). specifications promise. We Phone +49-7731-8673-0
The range from 790 to 822 confirm that it attenuates Fax +49-7731-8673-17
MHz is a transition region signals more than 50 dB in Model SMF 790
where attenuation gradually the range 815-1000 MHz. We Function LTE Stop Band Filter
changes from single decibels took two additional meas- Pass band 5-790 MHz
to over 50 dB. urements at -10 dB and -30 Pass Band Attenuation 1 dB typ.
In order to check whether dB. As this happened at 799 Stop Band 822-1000 MHz
the SMF 790 complies with and 807 MHz, we can cal-
Stop Band Attenuation 50 dB typ.
the published specifications, culate that the filter roll-off
we used a noise generator is: 20 dB per 8 MHz. That
and a signal analyzer capa- is a very steep transfer Expert Opinion
ble of measuring the signal characteristic what you can
Very steep frequency characteristics
up to1000 MHz. Perhaps evidently see in our screen
the term “noise generator” shots. We can do nothing + Low attenuation in the pass band and high
attenuation in the stop band
does not sound as a meas- but praise SPAUN for such Actual performance better than specification
urement equipment to non- excellent performance! It
Jacek Pawlowski
specialists but in fact it is safely blocks the LTE signals
–
TELE-satellite
a very useful device. When from entering your DVB-T/ None Test Center
Poland
combined with a spectrum T2 terrestrial receiver.
76 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 04-05/2012 — www.TELE-satellite.com