id: CAS
name: Chinese Academy of Sciences — GNSS Research Center (GIPP)
description: >
  CAS (Chinese Academy of Sciences, Institute of Geodesy and Geophysics, Wuhan)
  is an IGS MGEX analysis center. Primarily known for Global Ionosphere Maps
  (IONEX) and multi-GNSS differential code biases (DCB/OSB). The CAS GIM is one
  of the primary inputs to the IGS combined GIM (IGSG). Orbit, clock, ERP, and
  BIA products are also available through CDDIS and IGN mirrors.
  Note: distinct from WUM (Wuhan University) and SHA (Shanghai Astronomical Obs.).
website: https://www.gipp.org.cn/

servers:
  - id: cas_gipp_ftp
    name: CAS GIPP FTP
    hostname: "ftp://ftp.gipp.org.cn"
    protocol: ftp
    auth_required: true
    description: >
      CAS GNSS Ionospheric Products and Positioning (GIPP) FTP server.
      Externally inaccessible as of 2026-04 from outside China.
      Diagnosis: IP resolves (123.57.20.171, Alibaba Cloud), ICMP pings succeed
      (~270ms RTT), but FTP port 21 is silently dropped (TCP timeout). HTTP/HTTPS
      ports accept TCP connections but return no response. Root cause: Chinese
      network firewall (GFW) blocks FTP from foreign IPs; HTTP/HTTPS appear to be
      behind a CDN/WAF that does not respond to international traffic.
      Use CDDIS or IGN mirrors for CAS products instead (AAA=CAS entries available there).

products:
  # ── Ionosphere (GIM) ───────────────────────────────────────────
  # CAS is one of the primary IGS IONEX producers alongside CODE, JPL, ESA.
  # CAS GIM is weighted in the IGS combined (IGSG) product.
  # Access via this server requires Chinese network; use CDDIS/IGN instead.
  - id: cas_gim
    product_name: IONEX
    server_id: cas_gipp_ftp
    available: true
    description: >
      CAS Global Ionosphere Maps (GIM) — 1-hour and 2-hour resolution.
      One of the primary inputs to the IGS combined IGSG product.
    parameters:
      - {name: AAA, value: CAS}
      - {name: TTT, value: FIN}
      - {name: TTT, value: RAP}
      - {name: PPP, value: OPS}
      - {name: SMP, value: 01H}
      - {name: SMP, value: 02H}
    directory: {pattern: "product/ionex/{YYYY}/{DDD}/"}

  # ── High-rate Ionosphere (15-min GIM) ─────────────────────────
  # CAS also publishes a 15-minute IONEX series — useful for high-precision
  # single-frequency or ionosphere-constrained PPP.
  - id: cas_gim_15min
    product_name: IONEX
    server_id: cas_gipp_ftp
    available: true
    description: CAS high-rate 15-minute Global Ionosphere Maps
    parameters:
      - {name: AAA, value: CAS}
      - {name: TTT, value: FIN}
      - {name: TTT, value: RAP}
      - {name: PPP, value: OPS}
      - {name: SMP, value: 15M}
    directory: {pattern: "product/ionex/15min/{YYYY}/{DDD}/"}

  # ── Biases (DCB / OSB) ─────────────────────────────────────────
  # CAS produces multi-GNSS differential code biases (DCB) and observable-
  # specific signal biases (OSB) for GPS, GLONASS, Galileo, BDS, QZSS.
  - id: cas_bias
    product_name: BIA
    server_id: cas_gipp_ftp
    available: true
    description: >
      CAS multi-GNSS DCB/OSB bias products for all major constellations.
      Also available through CDDIS and IGN mirrors under AAA=CAS.
    parameters:
      - {name: AAA, value: CAS}
      - {name: TTT, value: FIN}
      - {name: TTT, value: RAP}
      - {name: PPP, value: MGX}
    directory: {pattern: "product/dcb/mgex/"}
