Especially due to new developments (turbine jets or huge models) and the new weight limit of
55 pounds (25kg) it is a matter of more and more complex and expensive flight objects. Unfortunately,
the development of radio controls did not cope with that. The legislator too did not provide for an
alternative as to control the models by this conventional technique. Nevertheless, EMCOTEC managed to
increase safety. Using the DPSI TWIN (Mini), two separate receivers (independent of
brand) can be assembled in the model already. If a breakdown or malfunction of a receiver (or crystal)
occurs, automatic switching to the "other" receiver takes place. After using 2 receivers it
is obvious to operate them on two different frequencies to avoid breakdowns due to doubled channel
occupation or other disturbances. This now is possible with the HF TWIN.
HF TWIN combines two standard HF modules (35MHz and 40MHz, 35MHz and 72MHz or 40MHz
and 72MHz) using corresponding electronics in the transmitter and radiates the signal via the regular
antenna. Due to this method, transmission takes place simultaneously on both frequency bands, i.e. both
receivers in the model always obtain the complete signal of the transmitter. The original HF modules
experience only minor changes. Usage of HF TWIN is currently limited to transmitter of
Graupner (console housed transmitter like mc24) because mechanical conditions influenced the development.
Due to the usage of two independent HF modules, breakdown of one HF module can not cause uncontrolled
behaviour.
Comparison of the MC24 HF TWIN to a competitive product (dual frequency module). Here it
is clearly to see that so called inter-modulation frequencies occur in the competitive product, which are
far above the limits of the CE guidelines. The attenuation of the used RC frequencies must be at least -60dB
to the neighboring frequencies. The MC24 HF TWIN has no inter-modulation frequencies and
does not disturb other channels. Output power (radiated transmitting power) is about the same in both cases.
In this diagram, the operation of the MC24 HF TWIN on the same channels (this is 35MHz
A-band and B-band) is shown just like the competitor does. Although only one inter-modulation frequency
with low amplitude occurs with the HF TWIN, the disturbances being much smaller than on
the competitor’s product, we do not offer the HF TWIN for operation with the 35MHz
A- and B-band. Simply because the CE guide lines, regulated by law, are not maintained! We only sell
products which conform to specifications regulated by law – to protect us and our customers.
As can be clearly seen, using 35MHz for both frequencies is not possible without tremendous effort,
because inter-modulation frequencies cause disturbance on adjacent channels. On the other hand it is
reasonable to transmit on two frequencies because some disturbances (atmospheric disturbances) can harm
the total band. HF TWIN does not alternate but transmit simultaneously on both frequency
bands. Therefore any manufacturer independent receiver is usable in connection with the DPSI TWIN.
HF TWIN corresponds to all aspects of metrological demands of the “Bundesnetzagentur”
(Federal Network Agency for Electricity, Gas, Telecommunications, Post and Railway; former regulatory authority
for telecommunication and Post (RegTP)) and therefore is the first product on the market which conforms to the
CE guide lines. For HF TWIN regular HF modules (preferred) as well as the new synthesizer
modules can be used. If only one frequency band should be transmitted on, the other HF module can simply be
removed from the transmitter (disconnect).
In conjunction with the DPSI TWIN, for the first time, secure remote control technique
is provided, which operates on two different channels. Two receivers in the model as well as two HF-modules
in the transmitter! Total redundancy and dual safety! All this while conforming to the regulations of the law!
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