System and method for the wireless signal transmission between a measuring head and a remote receiver

• US 5,949,352 A
• Filed: 10/23/1997
• Issued: 09/07/1999
• Est. Priority Date: 05/11/1995
• Status: Expired due to Fees

• Current Assignee: Marposs Societa' per Azioni
• Original Assignee: Marposs Societa' Per Azioni
• Inventors: Ferrari, Andrea
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Edwards, Jr., Timothy
• Application Number:
  US08/945,240
• Time in Patent Office: 684 Days
• Field of Search: 33/558, 33/561, 340/870.16, 340/870.19, 340/870.22, 340/870.23, 340/678, 340/679, 340/680, 340/681, 324/754, 324/756, 324/757
• US Class Current: 340/870.16
• CPC Class Codes: G01B 21/047 Accessories, e.g. for positioning, for tool-setting, for measuring probes
• CPC Class Codes: G01B 2210/58 Wireless transmission of information between a sensor or probe and a control or evaluation unit
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 19/28 using pulse code

Abstract

A system for transmitting a radio-frequency signal from a contact detecting probe (1), powered by a battery (4), to a remote interface (11), that includes the transmitting, by way of coded serial signals, of messages containing information regarding the state of the probe, the level of charge of its associated battery, and other possible control and identification information. In order to guarantee the repeatability of the delay time that cannot be avoided in the transmission of the change of state of the probe, the bit periods of the single bits that form the message are changed, with respect to a nominal bit period (TN) of the serial signal, on the basis of the delay or the advance at which there occurs the change of state, with respect to a theoretical instant (C0) pre-set within the nominal bit period. Each message comprises a number of bits that represent coded variables, and a start sequence (ST), clearly distinguishable with respect to the coded variables, and enabling the interruption of serial signals the transmission of which is in progress.

Claims

1. A system for the wireless signal transmission between a checking probe (1) and a remote receiver (11), comprising:

a sensor (3) located in the probe (1), for detecting a change in the state of the probe (1) and providing an associated checking signal;

a signal generator (5, 6, 13,

     15), connected to the sensor (3) and adapted for generating a signal comprising information about the state of the probe; and

a timing generator (16,

     17) connected to the signal generator characterized in that,

said signal generator (5, 6, 13,

     15) is adapted to generate a serial signal with a sequence of bits, coded to comprise said information about the state of the probe,

said timing generator (16,

     17) is adapted to define a nominal bit period (TN) for the bits of said sequence, and in that the system further comprises;

a detector (14), connected both to the sensor (3), for revealing the instant (C1, C2) within said nominal bit period (TN) when there occurs a change in the state of the probe (1) on the basis of the checking signal, and to the timing generator (16,

     17) for changing, according to said instant (C1, C2), the bit period (T1, T2) of at least one of the bits of said sequence in such a way that the time elapsing between the instant (C1, C2) of change of state and the end (F1, F2) of the sequence of bits assumes a substantially constant value (τ

).

2. A transmission system according to claim 1, wherein said probe is a contact detecting probe (1), and the sensor comprises a switch device (3) for providing a switch signal in consequence to a change of state of the probe (1), said switch device (3) being connected to the detector means (14).

3. A system according to claim 2, wherein said signal generator (5, 6, 13, 15) comprises a start generator (6) and a coder unit (5) for generating said sequence of bits, the start generator (6) being adapted for generating a constant signal (ST) that identifies the start of said sequence of bits.

4. A system according to claim 3, wherein the timing generator comprises:

a clock generator (17) and a generator unit (16) connected to the clock generator (17) for generating the bit periods of said bits, said detector comprising;

a counter (14) connected to the generator unit (16) for changing the bit period (T1, T2) of said at least one bit with respect to the nominal bit period (TN).

5. A system according to one of the preceding claims, wherein the remote receiver (11) comprises a digital section for the extraction of synchronism (25, 26, 27) with a logic correction unit (25) adapted for detecting and correcting the variations in the bit periods with respect to the nominal bit period (TN).

6. A system according to one of the preceding claims, comprising a radio-frequency transmitter (18) and a radio-frequency receiver (21), connected to the probe (1) and to the remote receiver (11), respectively, for the wireless transmission of said sequence of bits from the probe (1) to the remote receiver (21).

7. A method for the wireless transmission of a signal between a checking probe (1) and a remote receiver (11), the probe (1) having a sensor (3) for detecting a change of state of the probe and a transmitter section (13-19), the method comprising the steps of:

generating and transmitting, by the transmitter section (13-19), a signal comprising information regarding the state of the probe (1),

detecting the change of state of the probe (1), and

modifying said signal to change said information about the state of the probe,

characterized by the fact that said signal is a coded serial signal comprising a sequence of bits with a nominal bit period (TN), said sequence of bits being coded to comprise said information regarding the state of the probe (1), the method further comprising the steps of;

detecting the instant (C1, C2), within said nominal bit period (TN), at which the change of the state occurs, and altering the bit period (T1, T2) of at least one of the bits of said sequence, in such a way that the time elapsing between the instant (C1, C2) of change of state and the end (F1, F2) of the sequence of bits assumes a substantially constant value (τ

).

8. The method according to claim 7, in a system in which said checking probe is a contact detecting probe (1) with a switch device (3) for generating a switch signal, wherein said switch signal detects a change in the state of the probe (1).

9. The method according to claim 8, wherein the serial signal is sent from the transmitter section of the probe (1) to the remote receiver (11) by means of a radio-frequency transmission.

10. The method according to claim 9, wherein the nominal bit period (TN) defines a theoretical instant (C0) for the change of state of the probe (1), the time lag between the instant when the change occurs (C1, C2) and said theoretical instant (C0) being detected, and said bit period of at least one bit of the sequence being consequently altered.

11. The method according to claim 10, wherein the coded serial signal comprises a variable part coded according to a coding of a null average value.

12. The method according to claim 11, wherein said coding is of the Manchester type.

13. The method according to any one of claims from 7 to 12, wherein the sequence of bits comprises a constant part (ST) that identifies the start of said sequence of bits.