【正文】 vation to correct directly the ionospheric delay, that is, the precision of using IEFM to model ionospheric delay for single GPS users seems to has a breakthrough improvement and be similar to that of using the corresponding dual frequency GPS data to correct directly the ionospheric delays. The IEFM also suits to model the ionospheric delays for a kinematic based–single GPS receiver embeded in lowearth satellite with high rapid due to its good ability in distinguishing the daytime and nighttime of the earth ionosphere for an IPP. 6 A new strategy of correcting ionospheric delay for highprecision orbit determination for lowearth satellite using a single frequency GPS receiver the APRII scheme, ., Spacebased APR scheme Analyzed the shortings of using the previous methods to divide with high accuracy the earth ionosphere into different layers. Used GPS data to model global ionospheric TEC. Established a high precision grid ionospheric model. Discussed the possibility of finding out some local areas whose ionospheric construction and action have relatively better obvious law with respect to the other areas on a global scale. Designed a scheme for bining GPSgrounded data with GPSspaced data to divide efficiently the ionosphere into some layers. Given the corresponding formula of estimating the precision of the scheme. The preliminary precision estimation a nd the experimental results show the possibility and property of the above idea of dividing ionosphere into different layers according to application requirement and its implementation scheme. Based on the above research, the APRII scheme is presented which is a new and bined method of correcting the ionospheric delays of highprecision orbit determination for lowearth satellite using a single frequency GPS receiver. The preliminary experimental results based on two different sets of GPSgrounded data show that the APRII scheme can provide the effective ionospheric delay correction for highprecision orbit determination for lowearth satellite. 。初步的精度估算和試算結(jié)果表明，這種在局部區(qū)域進(jìn)行有效電離層分層的設(shè)想及給出的實(shí)施方法是可行的。 以上方法盡管是針對(duì)實(shí)時(shí)監(jiān)測(cè)要求提出的，但它完全可用于后處理情況。 針對(duì)這種狀況，我們通過(guò)設(shè)計(jì)能有效結(jié)合電離層延遲絕對(duì)量和相對(duì)變化量的抗差遞推過(guò)程，提出了一種可在以上不利條件下有效實(shí)時(shí)改正單頻 GPS 用戶(hù)電離層延遲的方法 — APRI 方案。研究發(fā)現(xiàn)，新方法可有效克服噪聲對(duì)分離儀器偏差的影響，而且儀器偏差相對(duì)穩(wěn)定并可有效進(jìn)行測(cè)段間及數(shù)日間預(yù)報(bào)。 1. (局部 )電離層延遲的高精度提取 系統(tǒng)論述和分析了影響利用 GPS 觀(guān)測(cè)精確提取電離層延遲信息的各類(lèi)因素。 二、具體研究工作的系統(tǒng)報(bào)告，主要集中在以下幾方面 : ① 研究如何利用單臺(tái)雙頻 GPS 接收機(jī)的觀(guān)測(cè)信息確定電離層延遲改正模型，為小范圍的單頻用戶(hù)服務(wù)； ② 研究如何實(shí)時(shí)分離 GPS 觀(guān)測(cè)中的儀器偏差與電離層延遲； ③ 研究如何建立較大區(qū)域的電離層格網(wǎng)模型，進(jìn)而初步設(shè)想利用中國(guó)地殼運(yùn)動(dòng)觀(guān)測(cè)網(wǎng)絡(luò)深入研究我國(guó)領(lǐng)域的電離層的電子濃度變化規(guī)律； ④ 研究單頻用戶(hù)在不利條件下，如何更好地利用電離層延遲改正信息； ⑤ 研究利用 GPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)的基本理論和框架方案； ⑥ 研究如何 綜合顧及電離層的周日、季節(jié)和年變化，進(jìn)一步提高利用 GPS 模擬電離層延遲的能力； ⑦ 研究如何實(shí)現(xiàn)星載單頻 GPS 低軌衛(wèi)星的精密測(cè)軌中的電離層延遲改正要求。 （ 3）利用相位平滑測(cè)碼數(shù)據(jù)進(jìn)一步精化了儀器偏差分離方法，探討了儀器偏 差的穩(wěn)定性。而以往的研究結(jié)果，均為后處 理方法，不能滿(mǎn)足 (準(zhǔn) )實(shí)時(shí)處理電離層擾動(dòng)的要求。 2） ACEVS 估計(jì)應(yīng)用于 GPS 電離層監(jiān)測(cè)的可行性的理論證明與模擬分析 不僅從理論上證明了 ACEVS 應(yīng)用于 GPS 電離層監(jiān)測(cè)的可行性，而且利用雙頻GPS 數(shù)據(jù)也成功地模擬了隨機(jī)電離層折射的 ACEVS 估計(jì)的特性，并發(fā)現(xiàn)，變樣本自協(xié)方差估計(jì)的統(tǒng)計(jì)特性對(duì)隨機(jī)電離層延遲變化是敏感的；初步討論和分析了GPS 觀(guān)測(cè)提供的 TEC 變化也適用于 ACEVS 方法應(yīng)用條件 . 3）建立利用 GPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)的框架方案 綜合 ACEVS理論及相關(guān)的結(jié)論和 GPS時(shí)序采樣的特點(diǎn)，初步給出一種基于 GPS的電離層擾動(dòng)監(jiān)測(cè)的框架方案。 6. 高精度修正星載單頻 GPS 低軌衛(wèi)星的電離層延遲的新對(duì)策 —— APRII方案，即空基 APR 方案 分析了現(xiàn)有方法無(wú)法保證高精度和高可靠性地進(jìn)行電離層分層這一嚴(yán)重不足；利用實(shí)測(cè)數(shù)據(jù)模擬全球電離層模型和建立高精度區(qū)域格網(wǎng)電離層模型，初步分析了在全球范圍內(nèi)尋找若干個(gè)電離層結(jié)構(gòu)和活動(dòng)相對(duì)較有規(guī)律的局部區(qū)域的可行性；設(shè)計(jì)了在選定的局部電離層區(qū)域，聯(lián)合處理地基和低軌空基用戶(hù)的 GPS觀(guān)測(cè)數(shù)據(jù)有效進(jìn)行 電離層分層的具體方法，給出了相應(yīng)的精度估計(jì)公式。 (7) How to meet the demand of correcting the ionospheric delay of highprecision orbit determination for lowearth satellite using a single frequency GPS receiver 1 Extracting (local) ionospheric information from GPS data with highprecision The factors are systematically described and analyzed which limit the precision of using GPS data to extract ionospheric delays. The precision of determining ionospheric delay using