- Sweep, digital video, analog video, DOCSIS® IP, and, PacketCable™ VoIP test available in one meter
- Manages and displays sweep files via the web using, immediate data synchronized over DOCSIS RF
- Full 4 to 1000 MHz frequency range
- Forward sweep option allows sweeping of analog, digital,, and DOCSIS carriers
- Compatibility with existing JDSU Stealth Sweep™ Systems,, assuring non-interfering forward and reverse sweep, operation compatible with today’s digital carriers
- New Digital Quality Index™ (DQI) provides an easy to, understand real time digital quality history (90 seconds)
- Rugged, lightweight design withstands rain, cold, heat,, bumps, drops, and other accidental mishaps
Network maintenance is a critical element in achieving the quality of service (QoS), necessary for cable operators to compete with alternative communications providers.
One core requirement of any cable network maintenance plan is to ensure that a, system’s broadband frequency response in both the forward path (downstream), and the return path (upstream) performs as required.
JDSU has a long history of integrating the high-level functions and advanced, technology necessary for maintaining cable networks into scalable hardware and, software platforms. Coupling the innovative Signal Analysis Meter (SAM) with, award-winning Stealth Sweep technology (Patent No. 5,585,842), JDSU delivers, sweep meter solutions unequalled in their ability to perform advanced tests and, measurements. These capabilities were integrated into the SDA-5000 series of, products, which soon earned its current industry-lead position.
JDSU introduced the DSAM (Digital Service Activation Meter) when DOCSIS, standards pushed the industry to adopt a common technology for delivering, flawless high-speed data and IP services. This award-winning, landmark meter, integrated JDSU’s well-known Service Analysis Meter (SAM) functions with, DOCSIS cable modem and PacketCable multimedia terminal adapter (MTA), elements and a PC-based management and file system.
Now, JDSU has introduced the next Wavetek™ Field Meter, the DSAM-6000, Digital Services Analysis Meter. Recognizing that maintaining cable networks, requires more than sweep, JDSU combined the DSAM’s video, audio, and data test, functions with the SDA’s downstream forward path and upstream return path, sweep functions and created a rugged, multitechnology handheld that performs, in the harshest environments.
Because it uses the SDA's powerful Stealth Sweep technology, the DSAM6000 can, be used with existing SDA rackmounted sweep gear, SDA-5500 and SDA-5510,, located at headend and hub sites. Additionally, the DSAM-6000B meters can sweep, side-by-side with SDA-5000 meters. Therefore, major modifications are not, required when DSAM-6000 meters are added to a department’s pool of meters.
||Signal Level Meter (SLM)
Traditional SLM test functions for analog video and audio levels as well as JDSU’s, extremely accurate digiCheck™ digital power level measurements are supported, by the DSAM6000. Furthermore, the ability to measure carrier-to-noise (C/N), on analog carriers comes standard. The DSAM-6000B can measure downstream, carriers to a full 1GHz and analyze 64, 128 and 256 QAM, including deep, interleave (i=128, j=4) modulation. Also included are MER and pre- and post-, FEC BER on both digital video and DOCSIS carriers, allowing technicians to, validate that digital services are received and they meet adequate margin and, quality specifications.
||Miniscan and Full Scan Modes
When measuring analog and digital as well as DOCSIS signals, technicians can see, high- and low-frequency channels and verify how much level headroom remains, when limits are activated. In miniscan mode, the DSAM monitors up to 12 channels, at a time and in full scan mode it monitors the entire channel plan, up to 999, channels. The results of both scans are displayed either as an easy-to-see bar graph, or in an informative table.
Tilt mode is used while sweeping to check the forward tilt of the channel levels at, the low and high ends of the frequency spectrum. The variances of the levels,, which are displayed at the bottom of the DSAM-6000 screen, indicate distortion, of the frequency spectrum. Based on these results, technicians know which, equalizer pad to select that will provide optimum flatness at the end of the line.
||Hum Analysis Mode
A hum measurement may be performed on a nonscrambled analog channel. Since, the instrument is battery powered, the measurement is independent of ground, loops and therefore is isolated from the line (mains). Severe hum is revealed on a, TV as either single (60/50 Hz) or double (120/100 Hz) horizontal bars across the, video screen. The DSAM6000 hum display indicates the composit level of all, frequency components below 1000 Hz as well as the fundamental hum frequency., The lower levels of adjacent frequencies as well as the fundamental are displayed, across a frequency graph. This is valuable in determining the source of hum, generation by displaying a telltale signature of the source (patent pending).
There are various elements in a network that compromise video quality. The, DSAM-6000B constellation mode displays patterns of data points on a graph,, which are easily interpreted, enabling technicians to detect and quickly diagnose, the source of digital video problems.
||Digital Quality Index™ (DQI) Mode
DQI is an indicator of the overall health of a QAM stream. This measurement, does a great job tracking intermittent problems and is unique only to JDSU. It is, represented by an easy to understand Index rating from "1" to "10" with ten being, the highest quality. DQI also catches errors sometimes missed by BER and Errored, Seconds measurements. It also displays a 90 second graphical history.
Modulation error ratio (MER) is the earliest indication of transmission quality, degradation resulting from noise, ingress, and composite distortions. An expression, of signal-to-noise ratio plus all other non-transient distortion signals, MER, also shows phase and amplitude distortions that may have been passed from the, headend. MER is the best overall quality measurement that can be performed on a, digital QAM carrier. JDSU has perfected this valuable measurement by optimizing, both custom hardware and proprietary software algorithms (Patent Nos. 6,061,393;, 6,233,274; 6,278,730 and 6,385,237). The result is accurate readings that far exceed, those reported from customer premise equipment such as digital settops.
Bit error ratio (BER) helps to quickly detect impulse changes in the system by, revealing when information is lost or corrupted at the bit layer. The DSAM-6000, measures BER by tracking the number of errored bits that are seen before forward, error correction (FEC), known as pre-BER, and the number of bits that cannot be, fixed by FEC, known as post-BER.
|Errored Seconds and Severely Errored Seconds Measurement
For troubleshooting connections that are suspected of intermittent bit errors, the, technician needs a means of capturing the presence of errors that have occurred, over a period of time. If an error has occurred during any second of elapsed time,, the errored second field increments by one. One error or multiple errors in the, same second is counted as one errored second. If more than 1 bit in 1 million bits, has errors occurring in the same second, the severely errored second register increments, by one. The errored seconds fields are conveniently included in the, digital level display.
||QAM Ingress Mode
Detecting the presence of ingress within the digital tier of carriers on the, downstream path is nearly impossible without turning off the service. The tightly, spaced QAM carriers hide any visual presence of unwanted forward ingress such, as CSO and CTB. An MER test will indicate that an issue exists but with the, DSAM6000 and the patented JDSU QAM Ingress mode the technician can, inspect what is actually going on beneath the digital “haystack” while still, remaining in service.
||Return QAM Generator
Standard on the DSAM-6000B, the Return QAM Generator is a mobile 16 QAM, transmitter. The ability to transmit a QAM-16 modulated signal back to the, headend is helpful for proving line capabilities for future data and voice channels, and for troubleshooting return path issues in the network.
Comprehensive Analog and Digital Testing on the Forward Path
The DSAM architecture incorporates analog and digital testing into a single user, interface. This allows the technician to select a specific channel or a scan of, channels without having to differentiate between analog or digital video, DOCSIS, high-speed data, or voice.
The active channel plan functions as a meter configuration file as well as a channel, lineup. An extensive selection of configuration elements establishes the type of, tests that can be performed on a particular channel for each channel in the plan.
Also inherent within a given channel plan are autotest configurations for analog,, digital, and DOCSIS services. Most configurations can be entered into the meter, directly or through the JDSU Test Productivity Pack (TPP) client/server application, software. Accessed via a PC, TPP manages channel plans and measurement, files for a collection of DSAM meters.
Networks with a history of multiple ownerships and diverse hardware architectures, are not a problem for the DSAM-6000. Supervisors can create multiple, channel plans for a specified group of meters or one channel plan for the whole, network. The channel plans can be deployed with plan parameters locked when, needed. Specific plans are easily selected from Configure mode, or in many cases,, directly from within a measurement mode. After selecting an active plan, a, technician can check the top of the measurement screen to confirm that it is the, correct plan. The channel plan name is included any saved measurement file for, reference. Using the channel plan to configure an Autotest, multiple tests can be, run in a short period of time with only two button presses.
Return and Forward Path Testing and Maintenance
A cable plant is a two-way path of information, enabling communication between, equipment. As a vital link between the CPE and the CMTS, the return path must, be aligned and kept free of ingress and noise.With digital services, limiting noise, and ingress becomes even more important because their effect may not be noticed, until service has significantly degraded.
The DSAM6000 is designed to test and maintain both the downstream forward, path and upstream return path. Its ability to sweep, along with conducting signal, level and quality measurements; ingress testing; verifying forward path signals;, and testing the level of ingress and noise provide the optimal approach to, maintaining the return path.
|DOCSIS Service Testing
The DSAM-6000B has a built in cable modem capable of performing quick and, accurate DOCSIS 2.0 RF and IP testing. This eliminates the need for a test modem, to verify cable modem connectivity or a computer to test the customer premises, equipments connection.
|Range and Registration
The DSAM-6000 can range and register with the headend CMTS to establish the, required configuration parameters and obtain a valid IP address on the network., The DSAM’s range and registration test verifies that a specific portion of the line, can support high-speed data transmission. Ranging results show how much, margin remains before communications in both the up and down streams, become disabled. Registration results validate that the CMTS is distributing, correct configuration files and IP addresses.
|DOCSIS IP Test
The DSAM performs IP tests including packet loss, throughput and ping over the, DOCSIS layer. The displayed results indicate which problems need to be tracked, down and fixed and those that should be reported as headend or IP troubles
|Voice Over IP (VoIP) Testing
The DSAM6000 offers two tiers of VoIP testing options and a range of VoIP, troubleshooting tools. One VoIP test enables services to be validated over a, DOCSIS connection (VoIPCheck™ Option). The other on networks that have, deployed PacketCable VoIP (TruVoice™ VoIP Option). The DSAM with its builtin, eMTA, can place calls as if they were from the CPE. This allows technicians to, fully test the VoIP registration process and verify dial tones from the network.
With VoIPCheck, the DSAM-6000B can test VoIP services independent of the VoIP, specification being used. VoIPCheck can segment RF issues from IP issues,, helping to eliminate organizational finger pointing. Packet statistics, including, packet loss, jitter, and delay, as well as call-quality results such as R-value and, MOS, are displayed on the screen.With its in-depth results analysis capability, the, DSAM-6000 can determine the source of call-quality problems, expediting the, troubleshooting process.
||TruVoice VoIP Option
TruVoice VoIP enables the DSAM6000 to measure packet statistics (packet loss,, delay, and jitter) and call quality (R-value and MOS) while on an active phone call, either placed or received with the DSAM’s eMTA. Listening to the call, the, technician can hear if there are any noticeable problems and review the, diagnostics displayed on the DSAM’s screen. The technician can call any phone, number on any system and measure call-quality throughout the call’s path to, locate the problem source quickly and easily.
|Enhanced Downstream Spectrum
Technicians need to be able to see how the network is behaving and troubleshoot, whether channels have shifted, have missing carriers, or are experiencing inchannel, frequency response problems. Since most technicians do not require a, fully featured and expensive spectrum analyzer, the DSAM, with its enhanced, downstream spectrum, can help provide a technician with an “everyday”, spectrum analyzer. It allows the user to choose between two resolution, bandwidths (RBW) settings, 330 KHz or 30 KHz and modify the amount of time, spent measuring each frequency step, or dwell time of the analyzer, between 1 and, 25 milliseconds. It also allows the user to see 4 MHz to 1 GHz, in 10 or 50 MHz, steps, without switching test modes. Furthermore, if viewing the return path, frequencies, the tech can turn on the internal low pass filter to eliminate noise, caused by the higher frequencies, providing a cleaner upstream view.
Service quality depends on transmitting signals with the best noise specifications, and the lowest intermodulation distortion. The majority of all transmission errors,, including digital, can be detected by measuring the frequency response of the, network. A sweep trace reveals every physical error in the network that influences, the transmitted signals. Also, since sweep results are independent of transmission, methods and formats, it is the most effective and efficient method for technicians, to set up the right gain versus frequency.
||Sweepless Sweep® Mode
For fundamental alignment of the forward distribution network, the JDSU, Sweepless Sweep mode provides an economical solution. This mode scans the, entire forward spectrum, displaying all levels across all frequencies (as defined by, meter configuration). The technician adjusts the reception of the node amplifier, with this scan and then normalizes the display by saving a reference. The resultant, display is a flat zero level trace. When the measurement point is moved to the, output of the RF amplifier, any changes due to the amplifier will be displayed as a, deviation (delta) from the reference display. The same reference is used as the, technician moves down the cascade, thus providing an excellent tool to align, succeeding amplifiers to compensate for the effects of each cable segment. To, isolate the effects of headend changes in levels, or to align portions of the, spectrum where there are no active carriers to reference, the forward sweep option, should be considered.
Forward Sweep Option
The DSAM-6000 offers fast forward sweep capabilities, especially in systems with, numerous digital channels. By referencing 64, 128 and 256 QAM signal types, the, DSAM6000 removes any worries about subscriber interference and prevents, sweep carriers from being injected into the guard bands. Referencing active, carriers, instead of transmitting sweep signals over active carriers, allows the, DSAM-6000B to sweep without degrading service quality.
Where there are absent carriers the SDA-5500 headend transceiver inserts a sweep, point to fill vacant spectrum frequencies. To remove effects of headend level drift,, this instrument monitors the levels and transmits new reference information with, every sweep. If the signal levels change in the headend, they won't effect the sweep, response measurement.
||Reverse Sweep Option
The return path can be problematic for two-way communications. It should be, tended to as often or more than the forward path and any impairments should, promptly be fixed. One of the best procedures to preserving a clean return path is, with an active reverse sweep maintenance plan. The DSAM-6000 has a built-in, reverse sweep transmitter, removing the need for externally generated carriers., A reverse sweep can uncover mismatch problems, revealed as standing waves, or, diplex filter roll-offs that can severely hamper the quality of services in the reverse, band.
|Headend Sweep Equipment
With the DSAM6000, one person can perform forward (downstream) and, reverse (upstream) path alignment simultaneously. For reverse testing with more, than one field technician, the rack mounted Model SDA-5510 Headend Reverse, Sweep Manager can perform reverse sweep on the same cluster of nodes for up to, ten different technicians. The SDA-5500 transceiver used in conjunction with the, model SDA-5510 receiver provides a full forward and reverse sweep alignment, solution. The SDA-5510 can also stand alone in remote hub sites for dedicated, reverse alignment applications.
||Field View™ Option
Field View provides the communication between JDSU’s PathTrak return path, monitoring systems and field meters such as the DSAM-6000B. A JDSU HSM-1000, sends spectrum measurements from PathTrak to the field meter, where the results, are displayed on the DSAM’s screen. By comparing local spectrum measurements, to those from PathTrak, field technicians can quickly resolve return path ingress, problems (Patent No. 6,425,132).
TechComplete™ Test Productivity Pack
TechComplete also helps managers communicate with their field staff. Test results, can be reviewed and experienced technicians at the hub can coach less-experienced, field staff with the remote DSAM feature, enabling more effective use of, time and resources.
||Upgrade DSAM Instruments to the DSAM6000
Models of the DSAM-2500 and up can be upgraded to the DSAM-6000B, maintenance tech meter. Any DSAM model below the DSAM-2500 must first be, upgraded to the DSAM-2500 or higher before the upgrade to the DSAM-6000 can, occur. All meters to be upgraded to the DSAM6000 may be sent back to th e, factory for hardware upgrades or upgraded on site by authorized JDSU service, personnel.
|DSAM-6000B Summary Features Matrix|
|Features||Included (X) or Option (O)|
|Analog Video||Levels,Tilt,Mini and Full Scan, C/N1||X|
|Digital Video||Ave Pwr, MER/EVM, Pre/Post FEC BER
BER for Deep Interleave (128,4)
|DS QAM Quality||Downstream Full Spectrum||X|
|DS Spec/Const.||Digital Quality Index™ (DQI) Score
|Sig Gen||Return QAM Generator (16 QAM or CW)||X|
|Upstream Physical Verification||Upstream 2-way connectivity, level with margins
US Spectrum for ingress
Field View option, view of headend Upstream Spectrum
|Modem Service Verification over RF||MER/EVM of Downstream QAM
Downstream FEC BER, Rng and reg, config file, CM and CPE MAC cloning
|IP Tests over RF and Ethernet||Roundtrip and segmented Packet Loss,US and DS throughput, Ping||X|
|VoIP Test||VoIPCheck DOCSIS VoIP Verification
PacketCable VoIP Testing2, includes VoIPCheck
|Other||Web Access Test, RF and Ethernet
View CM diagnostics page
|Network RF Performance Verification||Forward (Downstream) Sweep
Reverse (Upstream) Sweep
Two-ports for directional test points
|Common Test Utilities||One Key Autotest - including scheduled proof of performance tests*
Test Point Compensation
Ingress Resistance Test (IRT)
Fault Location using FDR feature in LST-1700 remote transmitter
|Browser||Open Web Browser3||O|
|Other||Home Ceritification (Closeout) Testing||O|
1C/N functional on all DSAM models with new hardware as of DSAM-6000 start of production.
2 VoIP available for North American PacketCable based on compatibility and availability for specific systems.
3 Function integrated with JDSU TPP Field Data Management Software, a client/server based PC application software used to
manage DSAM field meters and test data from a central location.
* Available in upcoming software release.
|Term||4 to 1000 MHz|
|Accuracy||±10 ppm at 77°F (25°C)|
|Tuning resolution||Analog 10 KHz, Digital 50 KHz|
|Channel bandwidth||Models ending in A, 8 MHz
Models ending in B, 6 MHz
|Level Measurement, Analog|
|Signal types||CW, video and audio (NTSC, PAL, and SECAM)|
|Range1||–40 to +60 dBmV|
|Resolution bandwidth||280 KHz|
|Accuracy2||±1.5 dB typical @ 25°C|
|Carrier-to-Noise||Input @ ≥6 dBmV
30 to 45 dB ±2 dB
45 to 48 dB ±3 dB
|Level Measurement, Digital|
|Modulation types||QPR, QPSK, QAM (DVB/ACTS)|
|Range1||–40 to +60 dBmV|
|Accuracy2||±2.0 dB typical @ 25°C|
|Two-Way Ranging Test|
|DOCSIS based||DOCSIS 1.0, 1.1 and 2.0|
|Upstream transmit range and diplexer crossover
(DOCSIS modes only)
|Models ending in A, 5 to 65 MHz 65/96MHz
(min. downstream DOCSIS center freq. 100 MHz)
Models ending in B, 5 to 42 MHz 42/88 MHz
(min. downstream DOCSIS center freq. 91 MHz)
|Upstream modulation||QPSK and 16 QAM as
instructed by CMTS
DOCSIS 2.0 US modulation
|Transmitter output||At 25ºC, maximum 55 dBmV
with 16 and 64 QAM and 58 dBmV
with QPSK, (typical)
|Downstream QAM Demodulation|
|Modulation type||64, 128 and and 256 QAM, ITU-T
J.83 Annex A, B or C (selectable)
|Input range (lock range)3||–15 to +50 dBmV
from 55 to 1000 MHz
|BER4||Pre- and Post-FEC 10-4 to 10-9|
|MER5||Range 64 QAM: 21 to 35 dB
Accuracy ±2 dB (typical)
Range 128/256 QAM: 28 to 35 dB
Accuracy ±2 dB (typical)
|DQI Channel types:||QAM modulation,symbol rate,
|EVM5||Range 64 QAM: 1.2% to 5.8%
Accuracy ±0.5% (1.2% to 2.0%)
±1.0% (2.1% to 4.0%)
±1.4% (4.1% to 5.8%)
Range 128/256 QAM: 1.1% to 2.4%
|Symbol rate||Annex A,
5.057 to 6.952 Msps (64 / 128 / 256 QAM)
5.057 Msps (64 QAM) and 5.361 Msps (256 QAM)
5.274 Msps (64 QAM) and 5.361 Msps (256 QAM)
Note: 128QAM Not defined for Annex B ITU-T J.83
|Test Point Compensation (User editable)|
|Forward path TPC||Max 100 dB Total
Forward external loss (dB): 0 to 50
Forward probe loss (dB): 0 to 50
|Reverse path TPC||Max 55 dB Total
Reverse internal loss (dB): 0 to 55
Reverse external loss (dB): 0 to 55
Reverse probe loss (dB): 0 to 55
|Reverse telemetry level (dBmV)||0 to 55|
|Reverse sweep insertion level (dBmV)||0 to 55|
|RF||75 ohm, F81 or BNC option
Max. sustained voltage 100 VAC, 140 VDC
|RS232||Via optional direct cable|
|Printer compatibility||Epson and Citizen|
|Ethernet||RJ45, 10 base T,TCP/IP and UDP supported|
|USB||v1.1 host mode, 150 mA
maximum slave (future firmware release)
|Shock and vibration||IEC 60068|
|Handle stress||IEC 61010|
|Safety – emissions||EN 55022|
|Safety – immunity||EN 61000|
|Upstream Spectrum (Ingress Scan)|
|Frequency range||Models ending in A, 4 to 65 MHz
Models ending in B, 4 to 45 MHz
|Sweep rate||Less than 2 seconds; Display scaling
5 and 10 dB/division; 6 vertical divisions
|Resolution bandwidth||280 kHz|
|Range1||–40 to 60 dBmV (typical)|
|Downstream Spectrum (Forward Scan)|
|Frequency range||4 to 1000 MHz|
|Sweep rate||Less than 2.5 seconds; Display
5 and 10 dB/division; 6 vertical divisions
|Resolution bandwidth||30 or 330 kHz|
|Dwell||1 ms to 25 ms|
|Span||50MHz or 10MHz zoom|
|Range1||4 to 100MHz, (typical)|
|Requires SDA-5500 (SDA Compatible mode)|
|Requires SDA-5500 (Single Reverse) or
SDA-5510 (Multiple Reverse) (SDA Compatible mode)
|Frequency range||5 to 1000 MHz|
|Display span||user definable|
|Display scale/range||6 vertical divisions
1, 2, 5, or 10 dB/division
|Sweep pulse occupied bandwidth||30 kHz|
|Stability||±0.5 dB, normalized
(dependent on stability of referenced carriers)
|Sweep rate||~1 second (78 channels, including
scrambled and digital signal types)
|Channel plan templates||(user editable on SDA Headend gear)
China-1; China-2; France; HDTP-NL; Ireland;
Japan; Jerold; Jerold-HRC; Jerold-IRC; NCTA;
NCTA-HRC; NCTA-SUB; NCTA-IRC;
NTSC-broadcast; OIRT-D/K; PL-B/G; PAL-UK
|Modulation type||128 and 256 QAM|
|Return QAM Generator|
|Frequency range||Models ending in B: 5 to 55 MHz
Models ending in A: 5 to 65 MHz
|Signal level range||8 to 58 dBmV|
|Signal modulation||CW or 16 QAM|
|Symbol rates (Msps)||1.28, 2.56, 3.84, 5.12|
|Cable Modem Diagnostic Page|
|Display||320 x 240, grayscale, Selectable back light|
|Language support||user interface and help system)
English in all models
No-charge second language
option of Spanish, French, German,
Hungarian, Japanese, Polish or Chinese
|Dimensions||Model 1500, 2500 and 3500:
4.75 x 9.75 x 2.75 in (12 x 25 x 7 cm)
Model 2600, 3600, and 6000:
4.75 x 9.75 x 3.25 in (12 x 25 x 8.25 cm)
|Weight||Model 1500, 2500 and 3500: 2 lb 12 oz (1.3 kg)
Model 2600 and 3600: 3 lb 4 oz (1.5 kg)
|Storage and operating temperature range||0 to 120°F;–20 to +50°C|
|Power||Hi-capacity Li-ion removable pack,
standard on DSAM6000
Hi-capacity Li-ion, 7 hours (typical)
|Charge time||Hi-capacity Li-ion, 10 hours (typical)|
|Power supply input||90-264 VAC, 47-63 Hz|
1 Total integrated power, detectable range
2 Accuracy for levels between –20 to 55 dBmV
Additional uncertainty ±0.5 dB across –20°C to 50°C
Additional uncertainty ±1.0 dB from 4 MHz to 15 MHz
3 Total integrated power, At 64 QAM
4 DSAM1500, 2500 and 3500 can support up to (I,J) = (128,1)
interleave for ITU-T J.83 Annex B; DSAM2600, 3600 and 6000 can
support up to (I,J) = (128, 4) interleave for ITU-T J.83 Annex B
5 Accuracy and behavior from 100 MHz to 1000 MHz for levels between
–5 to 50 dBmV (typical)
6 IP address is specified in the DOCSIS 1.1 and 2.0 operations support
system interface (OSSI) specifications