Note: Descriptions are shown in the official language in which they were submitted.
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
1
CONTROL DEVICE FOR A RADIO RECEIVER
This invention relates to a control device for providing signals at a RF
target reception
frequency.
Many types oi" communication links and networks are increasingly used for both
business
and domestic purposes, involving both static and mobile user terminals and
radio waves of
various frequencies. Today's sophisticated communication systems allow
constant access
to information and information providers even when on the move. A known kind
of radio
receiver incorporates a Radio Data System (RDS) capability which causes the
radio to
interrupt its present operating mode, eg. mute or play back of recorded music.
in order to
issue a special information announcement (after which. the interrupted
operating mode is
be resumed). However, the radio has to be specially adapted for this purpose.
An object of the present invention is to provide a control device which can
automatically
tune an external or auxiliary input signal to the frequency currently being
received by a
target receiver.
According to one aspect, the invention consists in a control device for using
noise from a
target receiver to tune an auxiliary signal to the frequency being received by
the target
receiver. The noise may be mixed with a modulated signal bearing the auxiliary
signal in
order to provide an output signal which contains a component at the target
reception
frequency.
According to another aspect, invention provides a control device for deducing
at Ieast one
possible reception frequency of a target receiver, the reception frequency
being the
fscqucncy to which the target receiver is tuned, and providing sisals at said
at least one
deduced frequency.
The present invention may be used in combination with many kinds of
communication
system, and may automatically tune an external or auxiliary input signal to
the frequency
ctuzeatly being received by au RF receiver within the communlc3lion SySiCril.
It InBy
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
interrupt the cuzrcntly selected RF signal, and allow the RF receiver to
receive the
incoming signal of interest by converting it to the frequency to which the RF
receiver is
currently tuned i.e. the target reception frequency. This provides the
automatic reception of
information without the need to alert the user to the fact that a signal of
interest has been
sent, and without the need for the user to manually alter any of the tuning
states of the
receiver to receive the incoming signal. At the end of the transmission of
interest, the
device allows the original RF signal transmission reception to resume. This is
particularly
useful in the case of a radio receiver in a car. In this case, the incoming
signal, such as a
telephone call, or information announcement; can . be transmitted through the
speaker
system of the existing car radio.
In one embodiment, the control device operates in combination with a
superheterodyne RF
receiver in a communication system. The control device tunes its transmission
frequency to
a RF target reception frequency by extrapolation from the currently defined
local oscillator
frequency of the target superheterodyne RF receiver, as determined by the
detection of
oscillator noise propagated at the target superhetcrodyne receiver's antenna
input. rn other
words, the control device uses the local oscillator frequency to extrapolate
the current
target RF reception frequency and then tunes the frequency of its transmission
signal to the
same frequency as that to which the target 1tF receiver is currently tuned so
that the control
device's transmission frequency signal can be received by the target RF
receiver.
The control device may be switched between a standby mode and a function mode
When in a standby mode, the control device may allow the free uninterrupted
passage of
normal signals from the antenna to the receiver. ?his standby mode xnay also
include
continuous or intermittent scanning of the noise on the receiver antenna
input, including
that from the local oscillator, using the data obtained to deduce the station
frequency to
which the receiver is currently tuned.
When in a function mode, the control device may detect a transmitted signal at
the external
ar auxiliary signal input, and once detected, mute the antenna signal
automatically, sad
replace the antenna signal with a signal generated by an internal R.p
modulator at the same
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
frequency as that to which the receiver is tuned. but avoiding transmitting
any interference
on the antenna. This results in the transmission of an external or auxiliary
input signal
using the audio-visual system of, for example, a radio or television, in the
same way as if
the external or auxiliary input signal - for instance a voice audio message -
were coming
from the currently selected radio or television station.
The external or auxiliary input signal may be generated by a number of
different sources,
for example, a PA microphone, an in-vehicle mobile phone, a CB-radio, an in-
vehicle
intercom, a pager or mobile phone messaging system, a portable computer, a
home-security
or a child-minding system, an inteznet e-mail iinlc, or any combination of the
foregoing.
In one embodiment, the oscillator frequency of the target receiver may be
determined by
the detection of local oscillator noise propagated at the target receiver's
antenna input.
In another embodiment, the control device may alternatively or additionally
detect a
broader range of the noise propagated at the target receiver»s antenna input
and provide
signals at deduced frequencies extrapolated from each noise frequency at which
there is a
noise signal above a predetermined level. The control device arrives at the
deduced
frequencies by processing each of the deduced frequencies as if it were a
noise signal from
the local oscillator of the target receiver. In this manner, the control
device provides a
spectrum of signals, at least one of which is at a frequency to which the
receiver is tuned.
In a further embodiment, the control device may perform a frequency scan to
determine
what frequencies are being used for broadcast purposes in the locality and
provide signals
for the target receiver at these deduced frequencies.
Certain embodiments of the present invention will now be described, by way of
example
only, with reference to the accompanying fzgurcs which show:
Figure 1 is a diagram illustrating an automatic RF control device;
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
4
Figure 2 is a diagram illustrating an automatic RF control device embedded in
a telephone
and the use thereof with receiver equipment;
Figure 3 is a diagram illustrating an automatic RF contzol device adapted for
incorporation
into s vehicle;
Figure 4 is a diagram illustrating an automatic RF control device which is in
wireless
communication with an antenna line; and
Figure 5 is a diagram illustrating an automatic RF control device
incorporating a mixer.
Figure 1 shows an automatic RF control device 10 according to the present
invention
positioned in the antenna signal path 12a, 12b between an RF antenna 14 and a
radio or
television superheterodyne receiver 16. The control device 10 has an auxiliary
input 18 for
an audio, data and/or video signal for voice, text and/or video insertions,
and operates as
follows:
In a stand-by mode, the device of the present invention can, using detector
20, continuously
or intermittently scan the RF noise on the receiver antenna input I2b, and
deduce the
station frequency to which the receiver is tuned at any given time from the
frequency being
generated by the Local oscillator (Z,0) circuitry of the receiver 16 which is
propagated to the
receiver antenna input 12b, as a non-utilised, but detectable noise signal.
'When an input signal of interest is received at the device auxiliary input
18, the device is
switched to an operation mode in which the existing antenna signal is
automatically muted,
and replaced with a signal gcacrated by an internal RF modulator 22 at the
same freque~tCy
as the channel to which the receiver 16 is currently tuned, but without
transmitting
undesirable or illegal interference on the antenna 14. Once the input signal
stops, the device
switches back to standby mode and, either immediately, or following a pre-
defined pause,
the original channel fiequcncy reception continues.
An alternative embodiment of the automatic control device is better adapted to
cope with
systems in which local oscillator noise propagation is supressed. The
automatic control
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
S
device of this embodiment scats the RF noise on the receiver antenna input and
determines
the frequencies of all noise signals having at least a predetermined
amplitude. The
automatic control device then deduces a possible reception frequency for each
noise
frequency by treating each noise frequency in turn as if it were the actual
local oscillator
noise signal.
When an input signal of interest is received at the auxiliary input I8 of the
automatic
control device, it mutes the existing antenna signal and replaces it with
signals generated
by RF modulator 22 at the spectrum of possible reception frequencies which
were deduced
from the noise frequencies. It will be appreciated that at least one of the
signals in the
spectrum will likely be at the frequency to which the target receiver is tuned
A further preferred embodiment of the automatic control device is shown in
Figure 6. The
control device 60 comprises a modulator 62 which receives the auxiliary signal
and which
produces a signal onto which the auxiliary signals are modulated. The
automatic control
device 60 further comprises a mixer 64 to which are supplied the modulated
signal from
modulator 62 and the noise detected from the target receiver. The mixer 64
produces, for
each component of the target receiver noise, two new modulated frequencies,
one of which
corresponds to the sum of the two mixed frequencies, and the other
corresponding to the
difference between them. The system is arranged (by preselection of the earner
frequency
of modulator 62) such that the signal produced by mixer 64 at the differential
frequency of
the mixture of the target receiver local oscillator noise frequency and the
output of
modulator 62 will match the actual reception frequency of the target receiver.
Thus, like
the previous embodiment, a spectrwm of signals are produced by the control
device, one of
which is the auxiliary signal modulated at the reception frequency of the
target receiver.
The automatic control device according to this embodiment is simple to
implement and
avoids intelligent target signal deduction and transmission signal synthesis
by simply
mixing all the noise signals from the target receiver with a predefuned
frequency produced
by modulator 62. Consider the following example:
A radio, one of a particular genre, has an internal reception frequency of
I0.7MHx. The
radio is a superheterodyne receiver and has a local oscillator which produces
a signal of
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
6
adjustable frequency, Fio, which is mixed into incoming radio signals to mix
them down to
the 10.7MHZ reception "window" of the radio. In this example, the control
device
modulates the auxiliary signal (with which it is desired to replace the
existing sig~aal
received by the radio) on to a 10.7MHZ carrier. The modulated signal is then
mixed into
the noise from the antenna lint of the radio and is supplied as an input to
the radio (in place
of the existing reception signal). Sinec the antenna line noise contains noise
from the
radio's local oscillator at frequency Fio, this new input signal contains a
component whose
frequency is Ft,o-10.7 MH,, i.e. the difference between the radio's local
oscillator frequency
and the frequency of the auxiliary signal carrier. At the radio, this
component is mixed
with the radio's local oscillator signal to produce a difference frequency of
FLO - (FLO - 10.7
\~i~) = 10.7MH", so that the auxiliary signal is received at the radio's
internal reception
frequency.
Any of the above described embodiments can be supplemented by providiung the
automatic
control device with a memory 24 containing a list of the frequencies of radio
stations in the
locality. The list can be used to test the likelihood of detected noise
signals corresponding
to the actual frequency to which the target receiver is tuned. The list may
even be
prioritised in accordance with known preferences of the target receiver_
The automatic control device could also be augmented by a feed-back detection
process. A
test signal could be emitted by the automatic control device and the noise
emitted by the
target receiver could be analysed by detector 20 for feed back corresponding
to the test
signal which would indicate that the automatic control device has correctly
targeted the
receiver.
Tn this way, the device enables the presentation of an external audio, video
and/or data
signal over the receiver in, for example, a radio or television, exactly as if
the audio, data
and/or video message was coming from the sdected radio or television station.
This device
also has the advantage that the user can receive transmitted signals without
any manual
tunin~e or the need to manually operate any switches or use any hand-held
receivers. The
output from the radio or television chanunel. currently in use is interrupted
and replaced with
the transmitted signal in audio, video andlor data form.
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
7
The input signal may originate as pan of a PA microphone system forming part
of an
institutional entertainment system, or a commercial infozmation bulletin
system. This
would allow messages to be delivered over an institutional PA system without
the
inconvenience of having to switch off an existing broadcast, and manually tune
into the PA
broadcasting frequency or switching between audio inputs. The existing
broadcast would
merely be interrupted until the PA message was completed, then the original
broadcast
would resume.
As shown in Figure 2, the automatic RF control device 30 may form part of a
hands free'
module in an in-vehicle mobile telephone 26. The control device 30, embedded
in the
telephone, receives signals on its auxiliary input (18, Figure 1) from the
sound producing
circuit 28 of the telephone 26. The automatic control device 30 communicates
with the
antenna line 32 of the in-vehicle radio 34 by way of Line 36, and its is thus
capable of
replacing the channel presently broadcast by the radio 34 with signals firom
the telephone
26. Thus, the driver of the vehicle is able to safely and audibly receive
incoming calls
without having to stop the vehicle to operate the receiver or to turn off the
radio.
When installed in a vehicle, the automatic RF control device can provide the
core of an
in-vehicle intercom system. The audio input from, for example, the front of a
vehicle, may
be output through the radio spealtezs in the rear of the vehicle by
intemtption of the radio
station currently being broadcast. Likewise, an existing in-vehicle intercom
system can be
used to form the basis of an embodiment of the invention.
Further, in combination with text to speech processing, the automatic RF
control device
could be used to allow pager or e-mail messages to be audibly presented by
intenvption of
a cuaently active radio or television channel.
Another use of the automatic RF control device is as a replacement to
traditional car
navigation systems employing graphic displays. These systems, since they
represent a
dangerous disuaction to drivers, may well be restricted in their use or made
illegal to
drivers. Existing products which combine car hi-fi and 'talking' car
navigation systems
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
8
exist, but are expensive since they integrate quality hi-fi systems with
dedicated
multi-media PCs.
However, the automatic RF control device of the present invention makes it
possible to
adapt any standard PC or PDA with GPS and software to provide requested
navigational
data for a fraction of the cost of a dedicated system. In addition, since the
PC or PDA is not
a dedicated system, it can also be used fox navigating other vehicles and
transportation
means, such as boats. However, PCs or PDAs typically have sub-standard sound
systems
with speakers which are inadequate and provide sound that is too quiet or of
too poor a
quality to be heard in a vehicle over engine and road noise. The automatic RF
control
device not only allows the navigational information to be of improved quality
by feeding
the sound througlx the in-vehicle hi-fi speakers, but also allows the user to
listen to the
radio during a journey and obtain the navigarional information at appropriate
times without
having to adjust the radio, since the system will automatically interrupt the
current radio
programme during delivery of the navigational information.
FM RDS-TMC (Radio Data System - Traffic Message Channel) is well known and
enables
broadcasters to insert traffio-rclated messages for motorists into ordinary
radio
programmes, using a sub-carrier which is only detected by compatible car
radios. However,
this system requires the motorist to be equipped with a compatible car radio
capable of
receiving these inserted traffic-related messages. The automatic RF control
device can be
used in combination with any existing radio anywhere in the world to provide
the same
progrannme interruption and message delivery system. In addition, this device
is simplex
and therefore also cheaper than existing RDS-compatible radios. Figure 3
illustrates the
provision of the automatic control device 40 in the antenna. Iine built into a
vehicle. The
antenna line 4Z leading from the automatic control device 40 may be connected
to a radio
44 installed in the facie 46 of a vehicle at production, or later.
Home-security ox child-minding systems could be augmented by the automatic RF
control
device of the present invention, which would allow any detected audio signal
to be
displayed remotely as a video, teletext or voice output to alert an operator
to potential
problems.
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/01352
9
Internet e-mail links could use the automatic RF control device of the present
invention to
display e-mail messages - or even intemet pages - on a TV set as video,
teletext or voice.
In the case of video and/or teletext presentation the device would have to
incorporate video
and/or teletext modulator and synthesiser circuitry. It will be appreciated
that the
autotuatic control device need not be incorporated in the apparatus providing
the auxiliary
signals {for example, as shown in Figure 2). The automatic control device and
the
apparatus providing the auxiliary signals for the control device could be
arranged to
communicate wirelessly to transfer the auxiliary signals to the automaxic
control device_
The wireless communication could be effected using a low cost, short range,
low power,
relatively high frequency link such as the "Bluetooth" system.
A further application of the automatic RF control device of the present
invention would
involve placing the device near the antenna path, rather than in the antenna
path, of the
target superhet~crodvne receiver. This would allow remote detection of the
local oscillator
noise signal, thereby allowing the transmission of a signal, at a frequency to
which the
target receiver is currently tuned, from a remote transmitter. Figure 4
illustrates a control
device 50 similar to that described with reference to Figure 1 but inductively
coupled 52 to
the antenna line 54.
This system could be used, for example, at night in built-up areas where loud
siren noise
may be undesirable, by police in cars. The police car could drive alongside a
target vehicle
and transmit an audio signal, intemtpting their radio reception, and request
them to stop
their car. Alternatively, this system could be used by emergency services to
request
motorists, who may not have heard the approaching emergency vehicle if they
had their car
radio playing at a high volume, to move aside to let them t~turaugh. Another
use may be in
car parks, where motorists about to park their vehicles could be transmitted a
message, for
example, warning them of the consequences of unauthorised parking, or
reminding them to
buy a parking voucher. Talking traffic and road signs of all kinds could
employ the system,
as well as road-side advertising transmitters.
Finally, any of the above-mentioned applications for the automatic RF control
device of the
present invention could be used in combination.
CA 02330638 2000-10-30
WO 99/57808 PCT/GB99/0135Z
Jt will be appreciated that modifications can be made within the scope of the
invention
