Telemetry device including a dynamic off-hook detector capable of operationg in a pulse-dialing environment

A telemetry device for collecting and transmitting data over a phone line to a central station, the telemetry device comprising:

• data collecting means for collecting data at a remote location;
• transmitting means, coupled to said collecting means, for transmitting said data over said phone line to said central station during an active state of said telemetry device in which said telemetry device seizes the phone line, said telemetric device otherwise being in a static state when said telemetry device is not seizing said phone line;
• static off-hook detector means, coupled to said phone line, for determining when a contending device goes off-hook and seizes said phone line while said telemetry device is in said static state;
• pulse dialing means, coupled to said phone line, for dialing said central station, said dialling means generating a dial pulse signal with alternating on-hook portions and off-hook portions, and
• dynamic off-hook detector means, coupled to said static off-hook detector means, for disengaging said telemetry device from said phone line during pulse dialing when during an on-hook portion of said dial pulse signal, said static off-hook detector means indicates that the contending device has seized the phone line.

A telemetry device for collecting and transmitting data over a phone line to a central station, said phone line exhibiting a loop current, said telemetry device comprising:

• voltage deriving means, coupled to said phone line, for deriving a voltage dependent on the loop current of said phone line, said voltage being designated the derived voltage;
• data collecting means for collecting data at a remote location;
• transmitting means, coupled to said collecting means, for transmitting said data over said phone line to said central station during an active state of said telemetry device in which said telemetry device seizes the phone line, said telemetry device otherwise being in a static state when said telemetry device is not seizing said phone line;
• static off-hook detector means, coupled to said phone line, for determining when a contending device coupled to said phone line goes off-hook and seizes said phone line while said telemetry device is in said static state;
• pulse dialing means, coupled to said phone line, for dialing said central station, said dialing means generating a dial pulse signal with alternating on-hook portions and off-hook portions, and
• a dynamic off-hook detector including:
• voltage drop detecting means, coupled to said voltage deriving means, for detecting when said derived voltage decreases to a predetermined voltage level thus indicating that the contending device coupled to said phone line has come off-hook during said active state;
• first disengaging means for disengaging said telemetry device from said phone line when said voltage drop detecting means indicates that the contending device coupled to said phone line has come off-hook during said active state, and
• second disengaging means for disengaging said telemetry device from said phone line during pulse dialing when during an on-hook portion of said dial pulse signal, said static off-hook detector means indicates that the contending device has come off-hook and seized the phone line.

A telemetry device for collecting and transmitting data over a phone line to a central station, said telemetry device comprising:

• a power supply, coupled to said phone line, for supplying power supply voltage to said telemetry device;
• data collecting means for collecting data at a remote location;
• transmitting means, coupled to said collecting means, for transmitting said data over said phone line to said central station during an active state of said telemetry device in which said telemetry device seizes the phone line, said telemetry device otherwise being in a static state when said telemetry device is not seizing said phone line;
• static off-hook detector means, coupled to said phone line, for determining when a contending device goes off-hook and seizes said phone line while said telemetry device is in said static state;
• pulse dialing means, coupled to said phone line, for dialing said central station at a predetermined time, said dialing means generating a dial pulse signal with alternating on-hook portions and off-hook portions, and
• a dynamic off-hook detector including:
• voltage drop detecting means, coupled to said power supply, for detecting when said power supply voltage decreases to a predetermined voltage level thus indicating that the contending device coupled to said phone line has come off-hook during said active state;
• first disengaging means for disengaging said device from said phone line when said voltage drop detecting means indicates that the contending device coupled to said phone line has come off-hook during said active state, and
• second disengaging means for disengaging said telemetry device from said phone line during pulse dialing when during an on-hook portion of said dial pulse signal, said static off-hook detector means indicates that the contending device has come off-hook and seized the phone line.

A method of operating a telemetry device coupled to a phone line at a remote location, said telemetry device residing in a static state until a predetermined time when said telemetry device enters an active state to seize said phone line to transmit data back to a central station over said phone line, said telemetry device including a static off-hook detector for determining when a contending device coupled to said phone line seizes said phone line while said telemetry device is in said static state, said telemetry device including a power supply coupled to said phone line for supplying power supply voltage to said telemetry device, said method comprising the steps of:

• pulse dialing by said telemetry device over said phone line to generate a dial pulse signal with alternating on-hook portions and off-hook portions when said telemetry device enters said active state;
• monitoring said static off-hook detector during said on-hook portions of said dial pulse signal to determine if the contending device goes off-hook and seizes said phone line;
• disengaging said telemetry device from said phone line during said pulse dialing if in said monitoring step a determination was made that the contending device is seizing said phone line during an on-hook portion of said dial pulse signal, and
• disengaging said telemetry device from said phone line when said power supply voltage decreases to a predetermined voltage level thus indicating that the contending telephone device coupled to said phone line has come off-hook during said active state.