Patent Application
20150142345
The present invention relates to power supplies for use in distribute communications networks and, more particularly, to power supplies capable of detecting and identifying network impediments.
Communications networks such as cable TV (CATV) networks include numerous components distributed throughout a dispersed geographic area. Impediments to proper or optimal operation of the CATV network (anomalies) include:
Cable Operators today use expensive, dedicated network analysis equipment to identify and troubleshoot these and other signal impediments. The root cause for these impediments or anomalies can be identified by the cable operator through experience and analysis of the measured signals.
In addition, chip sets from companies such as Broadcom (e.g., Broadcom DOCSIS 3.0 system-on-a-chip family) and Intel (e.g., Puma family) allow communications systems to be monitored in real time to for signal transmission characteristics. These chip sets do not detect and locate network impediments or anomalies associated with or unique to a particular communications system or that occur over time.
The need exists for improved systems and methods of detecting and identifying impediments in distributed communications networks that does not require expensive, dedicated network analysis equipment or the expertise of experienced cable operators.
A power supply system for use in a communications system comprises a power supply, a cable interface module, and a processor. The power supply is connected to a local supply, a utility supply, and the communications system. The cable interface module detects an FBC signal associated with the communications system. The processor executes a monitoring process in which the processor monitors the FBC signal for characteristics associated with at least one anomaly and generates a trap signal when an anomaly is detected.
The present invention may also be embodied as a method of providing power to a communications system comprising the following steps. A power supply is connected to a local supply, a utility supply, and the communications system. A cable interface module is arranged to detect an FBC signal associated with the communications system. The FBC signal is monitored for characteristics associated with at least one anomaly. A trap signal is generated when an anomaly is detected.
Referring now to
In the example network 20, a fiber optic cable system 32 carries fiber optical signals from the fiber optical splitter 30 to an optical node 34. The optical node 34 converts the fiber optical signals transmitted from the headend 24 to the premises 26 to electrical signals (downstream) and electrical signals transmitted from the premises to the headend 24 to fiber optical signals (upstream). The electrical signals are transmitted through a coaxial cable system 36.
The electrical signal output from the optical node 34 is transmitted using coaxial cable to a first coaxial splitter 40. The first coaxial splitter 40 splits the electrical signal into one or more electrical output signals. One representative electrical output from the first coaxial splitter 40 is connected to a first amplifier 42 which amplifies the electrical signal, allowing the electrical signal to be transmitted over greater distances. In the example communications network 20, the output from the first amplifier 42 is sent to a second coaxial splitter 44 and then to a second amplifier 46.
The output of the second amplifier 46 is sent to one or more taps 50, where the electrical signal is tapped and sent through drop cables 52 directly to individual homes or businesses forming the one or more premises 26. Each of the premises 26 contains Customer Premise Equipment (CPE) (not shown), which converts the electrical signal into a form usable by appliances, such as computers and televisions, within the premises 26.
The example power supply system 22 supplies power from a utility power source 60 to the optical node 34 and to the first and second amplifiers 42 and 46 through the same coaxial cable system 36 used to transmit electrical signals between the optical node 34 and the premises 26. The example power supply system 22 may further be capable of providing power from a local source 62 comprising batteries, an engine generator, solar power system, and/or other electrical generation means. The example power supply system 22 may further be embodied as an uninterruptible power supply (UPS). When embodied as a UPS, the example power supply system 22 is capable of supplying standby electrical power to the components (e.g., optical node 34, first amplifier 42, second amplifier 46) of the communications network 20 from the local source 62 when the primary power signal generated by the utility 60 falls outside of predetermined parameters.
The example power supply system 22 is further capable of performing qualitative evaluation of a network RF signature associated with the communications network 20. By using the example power supply system 22, and other such uninterruptible power supplies 22 distributed throughout the communications network 20, the operators of the communications network 20 can evaluate the network RF capabilities of the example communications network 20.
In particular, the example power supply system 22 includes a power supply 70 and a transponder system 72 for reporting power supply status, alarms, and other information to a monitoring system 72 associated with or located in the headend 24.
Referring now to
The example cable interface component 120 is, in the example transponder system 72, the Broadcom 3383D cable gateway chip (the Broadcom 3383 component).
As shown in more detail in
As shown in
The example cable interface component 120 of the example transponder system 72 is a DOCSIS 3.0 compliant component from Broadcom known as the 3383. The Broadcom 3383 component includes network analysis capabilities for diagnosing network problems or impediments commonly referred to as Full Band Capture (FBC). FBC can view the signal level on the entire downstream RF spectrum from 80 MHz to 1,000 MHz and provide a signal amplitude for individual frequencies within this spectrum. By analyzing these signal amplitudes through software, network impediments can be identified and categorized and, in many cases, the root cause of the impediment can be discerned.
Examples of impediments that can be identified through software analysis using the example transponder system 72 include:
For example, a ripple on the RF signal usually means an impedance mismatch in the coax. Impedance mismatches are often caused by corrosion in connectors. A micro reflections diagram tool of the example transponder system 72 can use the signal strength and frequency of the ripple to identify reflected power (i.e., some portion of the RF energy is reflected back towards the signal source when the primary signal encounters an impedance mismatch point in the network). Knowing the reflected power delay loop time and the propagation speed of the signal through the coax, the micro reflection tool can provide a close estimate of the distance from the power supply transponder to the offending location in the network. As generally discussed above, this location will often be a tap or splitter with a corroded connection.
The example transponder system 72 of the example power supply 22 implements Quality of Service (QoS) features network PHY layer quality at the power supply physical location in the network to be monitored. These features are implemented in the example transponder system 72 using the example cable interface component 120 with no additional hardware or firmware required. This text refers to the QoS features in the DSM33 as a QoS Network Probe or “probe”.
In addition to providing FBC (e.g., Broadcom FBC) capabilities, the firmware of the example transponder system 72 implements (1) Transport Stream Recording, (2) RF Constellation, and (3) Micro Reflections network analysis tools.
To support the Transport Stream Recording network analysis tool, the example transponder system 72 supports recording of the FCB data at user programmable recording periods. The recorded information will be stored in RAM for later download and analysis. The recorded stream can be triggered to capture an event occurring at any recorded frequency. This feature enables the logging and analysis of fast or impulse events that will not normally be captured during periodic FBC polls from the remote monitoring system.
As depicted in
Turning now to the Micro Reflections network analysis tool, the example transponder system 72 maintains a Microreflections web page that displays the impairments and provides the approximate distance(s) of those impairment(s). The upstream pre-equalization mechanism relies on the interactions of the (DOCSIS) ranging process implemented by the example in order to determine and adjust the cable modem (CM) pre-equalization coefficients. The intent is for the CM to use its coefficients to pre-distort the upstream signal such that the pre-distortion equals the approximate inverse of the upstream path distortion, so that as the pre-distorted upstream signal travels through the network it is corrected and arrives free of distortion at the upstream receiver at the cable modem termination system (CMTS).
In the example transponder system 72, impairment distance may be calculated as follows. Initially, the delay or spacing between each adaptive equalizer tap location may be equal to the symbol period, because it always has a parameter of adaptive equalizer taps/symbol equal to 1.
In this case, the ‘Impairment Distance’ is calculated as follows (assuming ‘Symbol Period’ is 0.195 μs):
TAP1=(195/1.17)/2=83 feet
(1.17 ns per foot for 87% velocity of propagation coax, divide by two to account for the reflection's round trip).
TAP2=(195*2/1.17)/2=166 feet
Alternatively, the delay between different adaptive equalizer tap locations can be a fraction of a symbol period. That is, the number of equalizer taps/symbol parameter is allowed to be 1, 2 or 4, resulting respectively in delay differences between adaptive equalizer tap locations of T, T/2 and T/4. In this case, the exact impairment distance calculations may differ from the example set forth above.
Referring now to
−10 dBc @<=0.5 μsec;
−20 dBc @<=1.0 μsec; and
−30 dBc @>1.0 μsec.
Referring now to
The factory calibration method includes the use of a cable loading generator (CLG) 220 operatively connected to the example power supply 22 containing the example transponder system 72. The CLG 220 comprises a single output port that supports 158 digitally modulated channels. The cable interface between the CLG and UUT must be kept as short possible and routinely inspected and swept on a Network Analyzer for peak linear performance. The factory calibration process effectively eliminates or offsets the effects of the non-linearity of the RF path on the transponder from the equalizer coefficients for each cable modem channel. Based on the internal structure of the IF filtering of the example transponder system 72, it may also be necessary to calibrate the coefficients based on the channel's position in the IF filter to compensate for any roll off seen at the filter edges. The fully loaded downstream is fed directly into the transponder at 0 dB per channel. The transponder locks onto each channel and retrieves the downstream equalizer coefficients. The negative of these coefficients are the calibration data. When performing any spectral measurement based on the equalizer coefficients, in-channel frequency response (ICFR), Channel Group Delay, or Phase, the factory coefficients that represent the PCB and component non-linearity are subtracted out prior to any calculations. An example would be performing a Fast Fourier Transform (FFT) on the coefficients to obtain the frequency response or group delay characteristics of a specific channel.
As described above, the example transponder system 72 is implemented using a cable interface chip 120 sold as the Broadcom 3383 series of DOCSIS components. In this case, the cable interface chip 120 supports spectral Full Band Capture (FBC) and is capable of being used for a broad range of network diagnostic tools. The following discussion thus assumes that the cable interface chip 120 as implemented provides the full range of network diagnostic tools of the Broadcom 3383 component or the equivalent.
Accordingly, the example transponder system 72 is capable of providing Full Band Diagnostics using SNMP Management Information Base (MIB) files, a Web graphical display, and a constellation display.
Referring initially to
In addition,
Turning now to
Referring now to
If upstream bonding is active, a vertical bar may be shown for each of the four possible bonded channels to allow the user to select a channel in the bonded group for pre-equalizer display and statistics display on that channel. In this case, a format similar to the bonded channel vertical bar display in the downstream constellation feature may be used.
A selection button on the micro-reflection display labeled “ICFR” may be used to display the In Channel Frequency Response (ICFR) for the upstream channel under observation. The FFT (Fast Fourier Transform) of the 24-tap pre-equalizer data in the graph in
In some situations, a predetermined number (e.g., 4) of additional taps (e.g., ingress cancellation taps) are arranged around the main tap. Such additional taps may be hidden or displayed. Ingress cancellation taps are quite powerful and can help identify the presence of aggressors under QAM channels. The example transponder system 72 does not display such ingress cancellation taps but shows warnings when ingress under the carrier is detected. Based on field experience, these taps may be graphically displayed.
Using functionality of the example cable interface component 120, the example transponder system 72 allows operators to automatically detect changes in RF signal levels resulting from: spurs, noise, tilt, drop-outs, and other undesirable spectral activity. The example transponder system 72 implements this feature as described below with reference to
Initially, a baseline or “good” spectral pattern is established. This pattern includes a nominal FBC scan with a “band” or range around the nominal values indicating a range of acceptable amplitudes for each scan point. The band or range can be manually configured or can be automatically setup by the SCR function through a set of FBC scans over time. During this setup period, amplitude values at each frequency will be compared to values from prior scans and the high and low values seen throughout the setup period are used as the high and low water marks for the frequency where they were identified. Any range of frequencies can be manually “disabled” (i.e., excluded from ongoing analysis) by configuring a high and low values for that frequency range to the maximum and minimum allowed values respectfully. This is done to create a “dead-band” that will be excluded from ongoing analysis (i.e., no actual FBC value will ever exceed these thresholds) and never contribute to future alarms.
Next, the transponder system 72 runs continuous scans on the defined spectrum to detect any signal amplitude above or below the pre-defined range (i.e., outside the water marks). Next, any scan containing readings outside the “acceptable” range is saved for later analysis. The SCR function can be configured to store offending spectral data using the following options:
Finally, an SNMP trap is sent to the operator identifying the exception. Up to one SNMP trap is sent per spectral capture containing offending data, even if that spectral data contains multiple offending data points.
The example transponder system 72 further implements automated data analysis methods to provide cable system operators with early notification of network anomalies. As one example, the example transponder system 72 executes a Capture, Analyze and Notify (CAN) sequence to combine Broadcom's FBC capability with near-real-time data analysis to provide automated network diagnostics. The example CAN sequence performs the following steps:
In general, a baseline is initially calculated as shown in
Referring initially to
At step 340, the method determines whether the baseline is to be calculated using the “watermark” method or whether the baseline is to be configured by the utility operating the example communications network 20. If the baseline is to be configured by the operator, the method moves to step 342 at which the user enters a user configured baseline level. The operator may use the raw FBC data stored in the FBC baseline database to generate a user configured baseline level. After the user sets the user configured baseline level, the baseline calculation process is complete and the process proceeds to step 344.
If the baseline is to be configured by using the “watermark” method, after step 340 the method moves to step 350. At step 350, FBC is executed numerous times over a period of time to get high and low threshold levels for the reference waveform. In particular, the raw FBC data is processed by selecting the highest and lowest levels associated with a plurality of waveforms. For each waveform, the highest and lowest levels within predefined bands may be used, in which case the high and low threshold levels may be a composite of the highest and lowest portions of numerous FBC data examples in each of the predefined bands. Further, average, filtered, or smoothed versions of the raw FBC data may be used to reduce the effects of spurious or transient signals. Using the “watermark” method, the baseline level is thus defined by or based on (e.g., average or median) high and low baseline levels that are empirically determined for a particular portion of the example communications network 20 associated with or including the example transponder system 72 including the cable interface module 120.
Alternatively, the baseline level may be defined using the high and low baseline levels calculated from the raw FBC data as a high baseline level and a low baseline level. In this case, the high and low baseline levels are not averaged or otherwise processed to obtain a single baseline level.
Once the baseline setup process is complete and the baseline level (or levels) is set, either by the “watermark” method or by user set parameters, the baseline level (or levels) is stored in the transponder system 72 for future use by a monitoring process implemented by the example transponder system 72. The power supply including the example transponder system 72 is now ready to be used in the monitoring process.
Turning now to
In particular, at step 370 data representing the new FBC signal is compared against an upper threshold level defined by the baseline level plus an offset Δ1. The offset Δ1 may be set such that the upper threshold level is equal to, greater than, or less than the high baseline level empirically determined during the baseline setup process. Further, different offsets Δ1 may be used in different bands within the relevant bandwidth of the FBC signal captured by the cable interface component 120.
Alternatively, if the baseline is determined by high and low baseline levels calculated from the raw FBC data, data representing the new FBC signal is compared at step 370 with the high baseline level. In this case, the high baseline level may be used directly or in combination with an offset to obtain a separate upper threshold level. If an offset is used with the high baseline level, the offset may be zero, positive, or negative, thereby adjusting the upper threshold level relative to the high baseline level as may be desirable for a particular portion of the example communications signal. Again, different offsets may be used in different bands within the relevant bandwidth of the FBC signal captured by the cable interface component 120.
If data representing the new FBC signal show that the new FBC signal is below the upper threshold level (no anomaly), the monitoring process proceeds to step 372. If data representing the new FBC signal show that the new FBC signal is equal to or above the upper threshold level (possible anomaly), the monitoring process proceeds to step 374 at which data representing the new FBC signal is stored as anomaly FBC data in an FBC anomaly database for further processing as will be described in further detail below.
At step 372, the data representing the new FBC signal is compared against a lower threshold level defined by the baseline level minus an offset Δ2. The offset Δ2 may be the same or different than the offset Δ1 and may be set such that the lower threshold level is equal to, greater than, or less than the low baseline level empirically determined during the baseline setup process. As with the example step 370, different offsets Δ2 may be used in different bands within the relevant bandwidth of the FBC signal captured by the cable interface component 120.
If the baseline is determined by separate high and low baseline levels calculated from the raw FBC data, the data representing the new FBC signal is compared at step 372 with the low baseline level. In this case, the low baseline level may be used directly or in combination with an offset to obtain a separate lower threshold level. If an offset is used with the low baseline level, the offset may be zero, positive, or negative, thereby adjusting the lower threshold level relative to the low baseline level as may be desirable for a particular portion of the example communications signal. Again, different offsets may be used in different bands within the relevant bandwidth of the FBC signal captured by the cable interface component 120.
If the data representing the new FBC signal show that the new FBC signal is above the lower threshold level (no anomaly), the monitoring process returns to step 362 and then the process repeats steps 370 and 372. If the data representing the new FBC signal show that the new FBC signal is equal to or below the lower threshold level (possible anomaly), the monitoring process proceeds to step 374. At step 374, the data representing the new FBC signal is stored as anomaly FBC data in the FBC anomaly database for further processing, again as will be described in further detail below.
Steps 370 and 372 thus define a parameter range having upper and lower threshold levels. If the new FBC signal is within that predetermined parameter range, the method returns to step 362 at which a new FBC data is generated and compared to the parameter range at steps 370 and 372. The monitoring process may be executed on command (asynchronously) or periodically. In the example monitoring process depicted in
Whenever an anomaly is detected, the data representing the new FBC signal is stored at step 374 as anomaly FBC data and, at step 376, a trap signal (e.g., SNMP trap) is transmitted to a destination such as the headend 24. The trap signal identifies the type of anomaly. Depending on factors such as the type of the anomaly and the frequency at which this type of anomaly occurs, the operator may take appropriate action to repair or replace a failed or degraded system component associated with that type and/or frequency of anomaly.
At a step 380, the operator is given the opportunity to restart the monitoring process by returning to the start monitoring step 360. If the operator elects not to restart at step 380, the monitoring process proceeds to step 382 at which the user is given the opportunity to reset the base line parameters by returning to the start baseline step 330 of the baseline setup process depicted in
In addition to saving and analyzing anomaly FBC data, the anomaly FBC data may be compared with previous and future corresponding anomaly FBC data to detect trends that are associated with projected failed or degraded system components even in the absence of a detected anomaly in the FBC data for any single power supply system. Based on these trends, appropriate maintenance may be performed before failure or degradation of system components.
Further, even absent the detection of an anomaly, sample FBC data associated with one power supply system 22 in the communications system 20 may be stored in a sample FBC database and compared with sample FBC data from another power supply system 22 of the communication system 20 to detect certain types of anomalies that may not be apparent by analyzing the FBC data at any single power supply system. For example, if first sample FBC data associated with a first power supply system differs in a substantive way from second sample FBC data associated with a second power supply system downstream of the first power supply system, even if neither the first nor the second FBC data corresponds to an anomaly, a difference between the first and second sets of FBC data may be associated with an anomaly that requires repair or maintenance.
In addition, the monitoring process may be configured to monitor characteristics of the FBC data for different types of anomalies and more than one type of anomaly at a time. In particular, the monitoring process may be configured to monitor characteristics in addition to or instead of high/low threshold levels such as overall shape of the waveform, slope of any portion of the waveform, discontinuities in the waveform. Additional steps similar to steps 360 and 362 may be executed in series or alternately with steps 360 and 362 to analyze the new FBC data for these other types of anomalies. The setting of reference levels may be automated in a manner similar to that of
The example transponder system 72 including the cable interface module 120 thus is configured to detect anomalies in the communications network 20 automatically and in real-time or near real-time. In addition, the example transponder system is capable of sending commands to the headend 24 or any other node in the communications network 20 to allow steps to be taken as necessary to repair the anomaly.
Examples of the data patterns that the FBD system will identify will be discussed below.
Level variation analysis may be performed to determine the time specific change in signal level over an entire band, often characterized by power level changes at a specific frequency such as 120 Hz. Such time specific changes in signal may be best analyzed using rapid, successive scans. Time specific changes in signal may indicate faulty or poorly designed AGC's, and lightning damaged couplers may allow AC power coupling onto the signal carrier.
This application (Attorney's Ref. No. P218168) claims benefit of U.S. Provisional Applications Ser. Nos. 62/053,763 filed Sep. 22, 2014, 62/037,461 filed Aug. 14, 2014, and 61/892,648 filed Oct. 18, 2013, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62053763 | Sep 2014 | US | |
| 62037461 | Aug 2014 | US | |
| 61892648 | Oct 2013 | US |
