the present invention relates to an improvement of a bluetooth transceiver when operating as master . the master continues to poll all connected slaves even while doing inquiry or page . in order not to disturb inquiry / page too much , a special type of polling is used that 0 ) does not depend on t poll ( polling shall be done as rarely as possible , just for holding the slaves ) 0 ) uses only short single slot packets 0 ) reaches all connected slaves with only one packet 0 ) does not allow a polled slave to return a packet in the following slave - to - master slot . doing this , the special polling ( named “ rescue beacon ”) consumes as little air capacity as possible . 1 ) polling is done every 125 ms ( not depending on t poll ) 2 ) bluetooth null packets are used . they consume only one bluetooth slot ( 625 μs ). it is also possible to use id packets ( consuming only a 312 . 5 μs half slot ), however , some manufacturers do not synchronize their slaves only to a received bluetooth access code , but also require a valid packet header . only if a valid packet header is received , can they synchronize their slave clock to the received packet . so a null packet is the better solution . 3 ) in addition , the am_addr field in the packet header is set to 000 binary , meaning that this packet is a broadcast packet that addresses all slaves at once . 4 ) the bluetooth specification forbids slaves to answer to a bluetooth null packet . a null packet as defined in bluetooth specification version 1 . 0b , is a packet which has no payload and therefore consists of the channel access code and packet header only , its total ( fixed ) length is 126 bits the null packet itself does not have to be acknowledged . fig5 a illustrates the operation of a bluetooth device acting as master of a piconet while performing a paging procedure . the master transmits and receives in alternate slots . it transmits in slots n , n + 2 , n + 4 . . . and receives in slots n + 1 , n + 3 , n + 5 . . . in the paging procedure , the master transmits two id packets per slot . the id packet has as its access code the paged slave &# 39 ; s device access code ( dac ) and it does not have a header or payload . the frequencies at which an id packet is transmitted is dependent upon a frequency hopping sequence determined from the paged slave &# 39 ; s bluetooth address ( bd_addr ). this frequency hopping sequence is f ( k ), f ( k + 1 ), f ( k + 2 ), f ( k + 3 ), f ( k + 4 ), f ( k + 5 ) . . . in the slot n , the first id packet is transmitted at a frequency f ( k ) and the second id packet in the slot n is transmitted at a frequency f ( k + 1 ). fig5 b , illustrates how the paging procedure is adapted in accordance with an embodiment of the present invention . the slot n + 2 is now occupied by a rescue beacon . this rescue beacon replaces the two id packets which would have been transmitted in slot n + 2 in the absence of the present invention . the paging sequence is otherwise unaffected . the rescue beacon is a null packet according to the preferred embodiment of the present invention ( a less desirable alternative would be an id packet ). the frequency at which the rescue beacon is transmitted is determined in accordance with the channel hopping sequence which is dependent upon the bluetooth device address ( bd_addr ) of the master transceiver and the phase within the sequence determined by the master clock . the channel frequency hopping sequence may be defined as g ( i ) where i is an integer . in the example of fig5 b , at slot n + 2 the phase of the bluetooth clock is given by m and consequently the frequency at which the rescue beacon is transmitted is represented by g ( m ). the null packet has as its access code , the channel access code which is derived from the bluetooth device address of the master unit and has a packet header which indicates that the packet is a broadcast beacon ( i . e . am_addr is set to 000 binary ). in the example of fig5 b , the n + 2 slot contains a rescue beacon because it is 125 ms since the beginning of the page procedure or 125 ms since the last transmission of a rescue beacon . it should therefore be appreciated that in slot n + x which is 125 ms after slot n + 2 , another rescue beacon will be transmitted . this rescue beacon will be a null packet identical to the preceding rescue beacon but will have a different frequency of transmission selected from the same channel hopping sequence but determined by the phase of the bluetooth master clock at the time of transmission apart from the punctuation of the train of paging messages by the replacement of a pair of id packets with a rescue beacon every 125 ms , the paging process is otherwise unaffected . referring to fig4 , according to an embodiment of the invention , the controller 60 is adapted to insert the rescue beacon ( null packet with channel access code at the correct channel hopping frequency ) at the correct time . the controller uses the header control signal 71 to insert the correct broadcast address into the header of the null packet and the access code control signal 69 provides the channel access code as the access code of the null packet . the access code control signal 69 is therefore changed from the device access code of the paged slave to the channel access code when the train of paging messages is to be punctuated by a rescue beacon . this change in the access code control signal 69 also affects a change in the hopping frequency sequence used . the frequency controller 48 will therefore switch to using the channel hopping sequence . the phase within the sequence is determined by the clock signal 59 from clock 68 without an offset being used . in a preferred embodiment , a rescue beacon is sent 125 ms after the start of the paging procedure and then once every 125 ms thereafter during the paging procedure . if a bluetooth device is not a master of a network , that is there are not already existing slave transceivers , the device will not implement the present invention when doing the paging procedure as there are no connected slaves . fig6 a illustrates the operation of a master transceiver when it is doing an inquiry procedure . it will be observed that the procedure is very similar to the paging procedure . a difference is that the id packets used have different access codes and in that the channel hopping sequence used is different as represented by the hopping sequence f ′( k ), f ′( k + 1 ). another difference is that the device expects fhs packets to be received instead of id packets the following description of the bluetooth fhs packet is taken from the “ specification of the bluetooth system , version 1 . 1 ; 22 , feb . 2001 ; section 4 . 4 . 1 . 4 :” the fhs packet is a special control packet revealing , among other things , the bluetooth device address and the clock of the sender . the payload contains 144 information bits plus a 16 - bit crc code . the payload is coded with a rate 2 / 3 fec which brings the gross payload length to 240 bits . the fhs packet covers a single time slot . the fhs packet is usually used in page master response , inquiry response and in master slave switch . in page master response or master slave switch , it is retransmitted until its reception is acknowledged or a time out has exceeded . in inquiry response , the fhs packet is not acknowledged . the fhs packet contains real time clock information . this clock information is updated before each retransmission . the retransmission of the fhs payload is thus somewhat different from the retransmission of ordinary data payloads where the same payload is used for each retransmission . the fhs packet is used for frequency hop synchronization before the piconet channel has been established , or when an existing piconet changes to a new piconet . in the former case , the recipient has not been assigned an active member address yet , in which case am_addr field in the fhs packet header is set to all - zeroes ; however , the fhs packet should not be considered as broadcast packe . in the latter case the slave already has an am_addr in the existing piconet , which is then used in the fhs packet header .” fig6 b illustrates how an embodiment of the present invention may be implemented during the inquiry mode . the train of id packets transmitted in the inquiry procedure is punctuated in the same manner as in the paging procedure as illustrated in fig6 b . the procedure for punctuation is identical to that described in relation to fig5 b . the slot n + 2 is now occupied by a rescue beacon . this rescue beacon replaces the two id packets which would have been transmitted in slot n + 2 in the absence of the present invention . the inquiry sequence is otherwise unaffected . the rescue beacon is a null packet according to the preferred embodiment of the present invention ( a less desirable alternative would be an id packet ). the frequency at which the rescue beacon is transmitted is determined in accordance with the channel hopping sequence which is dependent upon the bluetooth device address ( bd_addr ) of the master transceiver and the phase within the sequence determined by the master clock . although the present invention has been described in the preceding paragraphs with reference to various examples , it should be appreciated that modifications and variations to the examples given can be made without departing from the scope of the invention as claimed .